WorldWideScience

Sample records for high earth orbit

  1. On the Mitigation of Solar Index Variability for High Precision Orbit Determination in Low Earth Orbit

    Science.gov (United States)

    2016-09-16

    causing increased difficulty in achieving and maintaining high precision orbit predictions for satellites operating in low Earth orbit . In particular, the...Geodetic satellites with high precision satellite laser ranging data are used as test cases for the Naval Research Laboratory’s Orbit Covariance Estimation...forces imparted upon a satellite . For satellites in Low Earth Orbit (LEO), atmospheric drag forces are typically the largest source of force modeling error

  2. Advantages of High vs. Low Earth Orbit for SIRTF

    Science.gov (United States)

    Eisenhardt, Peter; Werner, Michael W.

    1989-01-01

    While the subject of this workshop, which we will refer to as ET (for Enlightenment Telescope), is a dazzling successor to the Hubble Space Telescope, its location is unlikely to be the Low Earth Orbit (LEO) used by HST. Locations suggested for ET include High Earth Orbit (HEO) and the moon. The first space telescope to occupy HEO will be the liquid helium cooled Space Infrared Telescope Facility (SIRTF). The selection of HEO for SIRTF was the outcome of a recent study led by the Ames Research Center which showed significant advantages for SIRTF in HEO vs. LEO. This article summarizes the main results of that study. We begin with a review of SIRTF's rationale and requirements, in part because the IR capabilities and low temperature proposed for ET make it something of a successor to SIRTF as well as to HST. We conclude with some comments about another possible location for both SIRTF and ET, the Earth-Sun L2 Lagrangian point.

  3. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  4. Non-numeric computation for high eccentricity orbits. [Earth satellite orbit perturbation

    Science.gov (United States)

    Sridharan, R.; Renard, M. L.

    1975-01-01

    Geocentric orbits of large eccentricity (e = 0.9 to 0.95) are significantly perturbed in cislunar space by the sun and moon. The time-history of the height of perigee, subsequent to launch, is particularly critical. The determination of 'launch windows' is mostly concerned with preventing the height of perigee from falling below its low initial value before the mission lifetime has elapsed. Between the extremes of high accuracy digital integration of the equations of motion and of using an approximate, but very fast, stability criteria method, this paper is concerned with the developement of a method of intermediate complexity using non-numeric computation. The computer is used as the theory generator to generalize Lidov's theory using six osculating elements. Symbolic integration is completely automatized and the output is a set of condensed formulae well suited for repeated applications in launch window analysis. Examples of applications are given.

  5. Sheath effects observed on a 10 meter high voltage panel in simulated low earth orbit plasma

    Science.gov (United States)

    Mccox, J. E.; Konradi, A.

    1979-01-01

    A large (1m x 10m) flat surface of conductive material was biased to high voltage (+ or - 3000 V) to simulate the behavior of a large solar array in low earth orbit. The model array was operated in a plasma environment of 1,000 to 1,000,000/cu cm, with sufficient free space around it for the resulting plasma sheaths to develop unimpeded for 5-10 meters into the surrounding plasma. Measurements of the resulting sheath thickness were obtained. The observed thickness varied approximately as V to the 3/4 power and N to the 1/2 power. This effect appears to limit total current leakage from the test array until sheath dimensions exceed about 1 meter. Total leakage current was also measured with the array.

  6. The earth orbiting space debris

    Directory of Open Access Journals (Sweden)

    Rossi A.

    2005-01-01

    Full Text Available The space debris population is similar to the asteroid belt, since it is subject to a process of high-velocity mutual collisions that affects the long-term evolution of its size distribution. Presently, more than 10 000 artificial debris particles with diameters larger than 10 cm (and more than 300 000 with diameters larger than 1 cm are orbiting the Earth, and are monitored and studied by a large network of sensors around the Earth. Many objects of different kind compose the space debris population, produced by different source mechanisms ranging from high energy fragmentation of large spacecraft to slow diffusion of liquid metal. The impact against a space debris is a serious risk that every spacecraft must face now and it can be evaluated with ad-hoc algorithms. The long term evolution of the whole debris population is studied with computer models allowing the simulation of all the known source and sink mechanisms. One of these codes is described in this paper and the evolution of the debris environment over the next 100 years, under different traffic scenarios, is shown, pointing out the possible measures to mitigate the growth of the orbital debris population. .

  7. High-precision repeat-groundtrack orbit design and maintenance for Earth observation missions

    Science.gov (United States)

    He, Yanchao; Xu, Ming; Jia, Xianghua; Armellin, Roberto

    2017-06-01

    The focus of this paper is the design and station keeping of repeat-groundtrack orbits for Sun-synchronous satellites. A method to compute the semimajor axis of the orbit is presented together with a station-keeping strategy to compensate for the perturbation due to the atmospheric drag. The results show that the nodal period converges gradually with the increase of the order used in the zonal perturbations up to J_{15}. A differential correction algorithm is performed to obtain the nominal semimajor axis of the reference orbit from the inputs of the desired nodal period, eccentricity, inclination and argument of perigee. To keep the satellite in the proximity of the repeat-groundtrack condition, a practical orbit maintenance strategy is proposed in the presence of errors in the orbital measurements and control, as well as in the estimation of the semimajor axis decay rate. The performance of the maintenance strategy is assessed via the Monte Carlo simulation and the validation in a high fidelity model. Numerical simulations substantiate the validity of proposed mean-elements-based orbit maintenance strategy for repeat-groundtrack orbits.

  8. High Cycle Life, Low Temperature Lithium Ion Battery for Earth Orbiting and Planetary Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA requires development of advanced rechargeable electrochemical battery systems for lithium ion batteries to support orbiting spacecraft and planetary missions....

  9. An autonomous navigation algorithm for high orbit satellite using star sensor and ultraviolet earth sensor.

    Science.gov (United States)

    Baohua, Li; Wenjie, Lai; Yun, Chen; Zongming, Liu

    2013-01-01

    An autonomous navigation algorithm using the sensor that integrated the star sensor (FOV1) and ultraviolet earth sensor (FOV2) is presented. The star images are sampled by FOV1, and the ultraviolet earth images are sampled by the FOV2. The star identification algorithm and star tracking algorithm are executed at FOV1. Then, the optical axis direction of FOV1 at J2000.0 coordinate system is calculated. The ultraviolet image of earth is sampled by FOV2. The center vector of earth at FOV2 coordinate system is calculated with the coordinates of ultraviolet earth. The autonomous navigation data of satellite are calculated by integrated sensor with the optical axis direction of FOV1 and the center vector of earth from FOV2. The position accuracy of the autonomous navigation for satellite is improved from 1000 meters to 300 meters. And the velocity accuracy of the autonomous navigation for satellite is improved from 100 m/s to 20 m/s. At the same time, the period sine errors of the autonomous navigation for satellite are eliminated. The autonomous navigation for satellite with a sensor that integrated ultraviolet earth sensor and star sensor is well robust.

  10. High resolution earth observation from geostationary orbit by optical aperture synthesys

    Science.gov (United States)

    Mesrine, M.; Thomas, E.; Garin, S.; Blanc, P.; Alis, C.; Cassaing, F.; Laubier, D.

    2017-11-01

    In this paper, we describe Optical Aperture Synthesis (OAS) imaging instrument concepts studied by Alcatel Alenia Space under a CNES R&T contract in term of technical feasibility. First, the methodology to select the aperture configuration is proposed, based on the definition and quantification of image quality criteria adapted to an OAS instrument for direct imaging of extended objects. The following section presents, for each interferometer type (Michelson and Fizeau), the corresponding optical configurations compatible with a large field of view from GEO orbit. These optical concepts take into account the constraints imposed by the foreseen resolution and the implementation of the co-phasing functions. The fourth section is dedicated to the analysis of the co-phasing methodologies, from the configuration deployment to the fine stabilization during observation. Finally, we present a trade-off analysis allowing to select the concept wrt mission specification and constraints related to instrument accommodation under launcher shroud and in-orbit deployment.

  11. Cycler orbit between Earth and Mars

    Science.gov (United States)

    Byrnes, Dennis V.; Longuski, James M.; Aldrin, Buzz

    1993-06-01

    A periodic orbit between Earth and Mars has been discovered that, after launch, permits a space vehicle to cycle back and forth between the planets with moderate maneuvers at irregular intervals. A Space Station placed in this cycler orbit could provide a safe haven from radiation and comfortable living quarters for astronauts en route to Earth or Mars. The orbit is largely maintained by gravity assist from Earth. Numerical results from multiconic optimization software are presented for a 15-year period from 1995 through 2010.

  12. Aiming at a 1-cm orbit for low earth orbiters : Reduced-dynamic and kinematic precise orbit determination

    NARCIS (Netherlands)

    Visser, P.N.A.M.; Van den IJssel, J.

    2003-01-01

    The computation of high-accuracy orbits is a prerequisite for the success of Low Earth Orbiter (LEO) missions such as CHAMP, GRACE and GOCE. The mission objectives of these satellites cannot be reached without computing orbits with an accuracy at the few cm level. Such a level of accuracy might be

  13. Orbit Propagation and Determination of Low Earth Orbit Satellites

    Directory of Open Access Journals (Sweden)

    Ho-Nien Shou

    2014-01-01

    Full Text Available This paper represents orbit propagation and determination of low Earth orbit (LEO satellites. Satellite global positioning system (GPS configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP. The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan to use a nonlinear filtering method for immediate orbit tasks requires more precise satellite orbit state parameters in a short time. Although the traditional extended Kalman filter (EKF method is widely used, its linear approximation of the drawbacks in dealing with nonlinear problems was especially evident, without compromising Kalman filter (unscented Kalman Filter, UKF. As a new nonlinear estimation method, it is measured at the estimated measurements on more and more applications. This paper will be the first study on UKF microsatellites in LEO orbit in real time, trying to explore the real-time precision orbit determination techniques. Through the preliminary simulation results, they show that, based on orbit mission requirements and conditions using UKF, they can satisfy the positioning accuracy and compute two indicators.

  14. Low Earth Orbit Satellite’s Orbit Propagation and Determination

    Science.gov (United States)

    2014-01-01

    Institute of Technology Email: honien.shou@xuite.net Abstract This paper represents orbit propagation and determination of Low Eearth Orbit(LEO...Arichandran, S. H. Tan, T. Bretschneider, High – Presicion Onboard Orbit Determination for Small Satellites - the GPS-Based XNS on X-SAT. 6th Symposium on

  15. Earth to Orbit Beamed Energy Experiment

    Science.gov (United States)

    Johnson, Les; Montgomery, Edward E.

    2017-01-01

    As a means of primary propulsion, beamed energy propulsion offers the benefit of offloading much of the propulsion system mass from the vehicle, increasing its potential performance and freeing it from the constraints of the rocket equation. For interstellar missions, beamed energy propulsion is arguably the most viable in the near- to mid-term. A near-term demonstration showing the feasibility of beamed energy propulsion is necessary and, fortunately, feasible using existing technologies. Key enabling technologies are large area, low mass spacecraft and efficient and safe high power laser systems capable of long distance propagation. NASA is currently developing the spacecraft technology through the Near Earth Asteroid Scout solar sail mission and has signed agreements with the Planetary Society to study the feasibility of precursor laser propulsion experiments using their LightSail-2 solar sail spacecraft. The capabilities of Space Situational Awareness assets and the advanced analytical tools available for fine resolution orbit determination now make it possible to investigate the practicalities of an Earth-to-orbit Beamed Energy eXperiment (EBEX) - a demonstration at delivered power levels that only illuminate a spacecraft without causing damage to it. The degree to which this can be expected to produce a measurable change in the orbit of a low ballistic coefficient spacecraft is investigated. Key system characteristics and estimated performance are derived for a near term mission opportunity involving the LightSail-2 spacecraft and laser power levels modest in comparison to those proposed previously. While the technology demonstrated by such an experiment is not sufficient to enable an interstellar precursor mission, if approved, then it would be the next step toward that goal.

  16. Mitigating Climate Change with Earth Orbital Sunshades

    Science.gov (United States)

    Coverstone, Victoria; Johnson, Les

    2015-01-01

    An array of rotating sunshades based on emerging solar sail technology will be deployed in a novel Earth orbit to provide near-continuous partial shading of the Earth, reducing the heat input to the atmosphere by blocking a small percentage of the incoming sunlight, and mitigating local weather effects of anticipated climate change over the next century. The technology will provide local cooling relief during extreme heat events (and heating relief during extreme cold events) thereby saving human lives, agriculture, livestock, water and energy needs. A synthesis of the solar sail design, the sails' operational modes, and the selected orbit combine to provide local weather modification.

  17. Airbreathing Acceleration Toward Earth Orbit

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J C

    2007-05-09

    As flight speed increases, aerodynamic drag rises more sharply than the availability of atmospheric oxygen. The ratio of oxygen mass flux to dynamic pressure cannot be improved by changing altitude. The maximum possible speed for airbreathing propulsion is limited by the ratio of air capture area to vehicle drag area, approximately Mach 6 at equal areas. Simulation of vehicle acceleration shows that the use of atmospheric oxygen offers a significant potential for minimizing onboard consumables at low speeds. These fundamental calculations indicate that a practical airbreathing launch vehicle would accelerate to near steady-state speed while consuming only onboard fuel, then transition to rocket propulsion. It is suggested that an aircraft carrying a rocket-propelled vehicle to approximately Mach 5 could be a realistic technical goal toward improving access to orbit.

  18. GALILEO ORBITER EARTH MAG RDR EARTH2 HIGHRES V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated high-resolution data from the Earth-2 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...

  19. GALILEO ORBITER EARTH MAG RDR EARTH1 HIGHRES V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated high-resolution data from the Earth-1 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...

  20. Triple Difference Approach to Low Earth Orbiter Precision Orbit Determination

    Science.gov (United States)

    Kwon, Jay-Hyoun; Grejner-Brzezinska, Dorota A.; Yom, Jae-Hong; Cheon, Lee-Dong

    2003-03-01

    A precise kinematic orbit determination (P-KOD) procedure for Low Earth Orbiter(LEO) using the GPS ion-free triple differenced carrier phases is presented. Because the triple differenced observables provide only relative information, the first epoch's positions of the orbit should be held fixed. Then, both forward and backward filtering was executed to mitigate the effect of biases of the first epoch's position. P-KOD utilizes the precise GPS orbits and ground stations data from International GPS Service (IGS) so that the only unknown parameters to be solved are positions of the satellite at each epoch. Currently, the 3-D accuracy of P-KOD applied to CHAMP (CHAllenging Minisatellite Payload) shows better than 35 cm compared to the published rapid scientific orbit (RSO) solution from GFZ (GeoForschungsZentrum Potsdam). The data screening for cycle slips is a particularly challenging procedure for LEO, which moves very fast in the middle of the ionospheric layer. It was found that data screening using SNR (signal to noise ratio) generates best results based on the residual analysis using RSO. It is expected that much better accuracy are achievable with refined prescreening procedure and optimized geometry of the satellites and ground stations.

  1. Extravehicular activity at geosynchronous earth orbit

    Science.gov (United States)

    Shields, Nicholas, Jr.; Schulze, Arthur E.; Carr, Gerald P.; Pogue, William

    1988-01-01

    The basic contract to define the system requirements to support the Advanced Extravehicular Activity (EVA) has three phases: EVA in geosynchronous Earth orbit; EVA in lunar base operations; and EVA in manned Mars surface exploration. The three key areas to be addressed in each phase are: environmental/biomedical requirements; crew and mission requirements; and hardware requirements. The structure of the technical tasks closely follows the structure of the Advanced EVA studies for the Space Station completed in 1986.

  2. Regional positioning using a low Earth orbit satellite constellation

    Science.gov (United States)

    Shtark, Tomer; Gurfil, Pini

    2018-02-01

    Global and regional satellite navigation systems are constellations orbiting the Earth and transmitting radio signals for determining position and velocity of users around the globe. The state-of-the-art navigation satellite systems are located in medium Earth orbits and geosynchronous Earth orbits and are characterized by high launching, building and maintenance costs. For applications that require only regional coverage, the continuous and global coverage that existing systems provide may be unnecessary. Thus, a nano-satellites-based regional navigation satellite system in Low Earth Orbit (LEO), with significantly reduced launching, building and maintenance costs, can be considered. Thus, this paper is aimed at developing a LEO constellation optimization and design method, using genetic algorithms and gradient-based optimization. The preliminary results of this study include 268 LEO constellations, aimed at regional navigation in an approximately 1000 km × 1000 km area centered at the geographic coordinates [30, 30] degrees. The constellations performance is examined using simulations, and the figures of merit include total coverage time, revisit time, and geometric dilution of precision (GDOP) percentiles. The GDOP is a quantity that determines the positioning solution accuracy and solely depends on the spatial geometry of the satellites. Whereas the optimization method takes into account only the Earth's second zonal harmonic coefficient, the simulations include the Earth's gravitational field with zonal and tesseral harmonics up to degree 10 and order 10, Solar radiation pressure, drag, and the lunisolar gravitational perturbation.

  3. Fuel Optimization for Low Earth Orbit Maintenance

    Directory of Open Access Journals (Sweden)

    Yong Jae Park

    2008-06-01

    Full Text Available The resolution of Earth images taken from a satellite has close relation with satellite's altitude. If a satellite has lower altitude, it gets a picture having better resolution. However the satellite will be exposed to heavier air drag and will spend more fuel to maintain its altitude for a desired mission. Therefore, in this study, the required fuel to maintain very low earth orbit(LEO with severe air drag is analyzed using optimization method such as collocation method. The required fuel to maintain the low altitude has significantly increased as the mission altitude is lowered and the solar activity is maximized. This study also shows that the fuel reduced by increasing the period of the satellite maneuver is very small, and that slightly increasing the satellite's mission altitude is much effective in reducing the amount of fuel to maintain its altitude. The calculated fuel to maintain very low earth orbit in this study would give useful information in planning the budget of fuel and cost for LEO satellites.

  4. Earth-like aqueous debris-flow activity on Mars at high orbital obliquity in the last million years.

    Science.gov (United States)

    de Haas, T; Hauber, E; Conway, S J; van Steijn, H; Johnsson, A; Kleinhans, M G

    2015-06-23

    Liquid water is currently extremely rare on Mars, but was more abundant during periods of high obliquity in the last few millions of years. This is testified by the widespread occurrence of mid-latitude gullies: small catchment-fan systems. However, there are no direct estimates of the amount and frequency of liquid water generation during these periods. Here we determine debris-flow size, frequency and associated water volumes in Istok crater, and show that debris flows occurred at Earth-like frequencies during high-obliquity periods in the last million years on Mars. Results further imply that local accumulations of snow/ice within gullies were much more voluminous than currently predicted; melting must have yielded centimetres of liquid water in catchments; and recent aqueous activity in some mid-latitude craters was much more frequent than previously anticipated.

  5. Earth Parking Orbit and Translunar Injection

    Science.gov (United States)

    Interbartolo, Michael

    2009-01-01

    The objectives of this slide presentation are to (1) Describe the general characteristics of the Earth Parking Orbit (EPO) and Translunar Injection (TLI) (2) List the general activities that occurred during EPO (4) State what went into verifying a working Saturn IVB S-IVB IU and a CSM GNC (5) Differentiate between a Free-Return Trajectory vs. a Hybrid Non-Free-Return Trajectory (6) Identify the crew monitoring task during the TLI Burn and (7) Identify the abort modes in the event of severe systems problems during the TLI timeframe

  6. Low-cost, high-resolution, single-structure array telescopes for imaging of low-earth-orbit satellites

    Science.gov (United States)

    Massie, N. A.; Oster, Yale; Poe, Greg; Seppala, Lynn; Shao, Mike

    1992-01-01

    Telescopes that are designed for the unconventional imaging of near-earth satellites must follow unique design rules. The costs must be reduced substantially over those of the conventional telescope designs, and the design must accommodate a technique to circumvent atmospheric distortion of the image. Apertures of 12 m and more along with altitude-altitude mounts that provide high tracking rates are required. A novel design for such a telescope, optimized for speckle imaging, has been generated. Its mount closely resembles a radar mount, and it does not use the conventional dome. Costs for this design are projected to be considerably lower than those for the conventional designs. Results of a design study are presented with details of the electro-optical and optical designs.

  7. Modeling Earth Albedo for Satellites in Earth Orbit

    DEFF Research Database (Denmark)

    Bhanderi, Dan; Bak, Thomas

    2005-01-01

    Many satellite are influences by the Earthøs albedo, though very few model schemes exist.in order to predict this phenomenon. Earth albedo is often treated as noise, or ignored completely. When applying solar cells in the attitude hardware, Earth albedo can cause the attitude estimate to deviate......, in which the Earth Probe Satellite has recorded reflectivity data daily since mid 1996. The mean of these data can be used to calculate the Earth albedo given the positions of the satellite and the Sun. Our results show that the albedo varies highly with the solar angle to the satellite's field of view......, and that the longitude of the satellite position is significant to the model output. The results also show that the calculated albedo is generally lower than it would be expected based only on the reflectivity data....

  8. Taurus Lightweight Manned Spacecraft Earth orbiting vehicle

    Science.gov (United States)

    Bosset, M.

    The Taurus Lightweight Manned Spacecraft (LMS) was developed by students of the University of Maryland's Aerospace Engineering course in Space Vehicle Design. That course required students to design an Alternative Manned Spacecraft (AMS) to augment or replace the Space Transportation System and meet the following design requirements: (1) launch on the Taurus Booster being developed by Orbital Sciences Corporation; (2) 99.9 percent assured crew survival rate; (3) technology cutoff date of 1 Jan. 1991; (4) compatibility with current space administration infrastructure; and (5) first flight by May 1995. The Taurus LMS design meets the above requirements and represents an initial step toward larger and more complex spacecraft. The Taurus LMS has a very limited application when compared to the space shuttle, but it demonstrates that the U.S. can have a safe, reliable, and low-cost space system. The Taurus LMS is a short mission duration spacecraft designed to place one man into low Earth orbit (LEO). The driving factor for this design was the low payload carrying capabilities of the Taurus Booster - 1300 kg to a 300-km orbit. The Taurus LMS design is divided into six major design sections. The Human Factors section deals with the problems of life support and spacecraft cooling. The Propulsion section contains the Abort System, the Orbital Maneuvering System (OMS), the Reaction Control System (RCS), and Power Generation. The thermal protection systems and spacecraft structure are contained in the Structures section. The Avionics section includes Navigation, Attitude Determination, Data Processing, Communication systems, and Sensors. The Mission Analysis section was responsible for ground processing and spacecraft astrodynamics. The Systems Integration Section pulled the above sections together into one spacecraft, and addressed costing and reliability.

  9. Possible Outcomes of Coplanar High-eccentricity Migration: Hot Jupiters, Close-in Super-Earths, and Counter-orbiting Planets

    Science.gov (United States)

    Xue, Yuxin; Masuda, Kento; Suto, Yasushi

    2017-02-01

    We investigate the formation of close-in planets in near-coplanar eccentric hierarchical triple systems via the secular interaction between an inner planet and an outer perturber (Coplanar High-eccentricity Migration; CHEM). We generalize the previous work on the analytical condition for successful CHEM for point masses interacting only through gravity by taking into account the finite mass effect of the inner planet. We find that efficient CHEM requires that the systems should have m1 ≪ m0 and m1 ≪ m2. In addition to the gravity for point masses, we examine the importance of the short-range forces, and provide an analytical estimate of the migration timescale. We perform a series of numerical simulations in CHEM for systems consisting of a Sun-like central star, giant gas inner planet, and planetary outer perturber, including the short-range forces and stellar and planetary dissipative tides. We find that most of such systems end up with a tidal disruption; a small fraction of the systems produce prograde hot Jupiters (HJs), but no retrograde HJ. In addition, we extend CHEM to super-Earth mass range, and show that the formation of close-in super-Earths in prograde orbits is also possible. Finally, we carry out CHEM simulation for the observed hierarchical triple and counter-orbiting HJ systems. We find that CHEM can explain a part of the former systems, but it is generally very difficult to reproduce counter-orbiting HJ systems.

  10. Orbit-Attitude Changes of Objects in Near Earth Space Induced by Natural Charging

    Science.gov (United States)

    2017-05-02

    Propagation; Magnetic Field; Geosynchronous Orbit ; Satellite Components; Electrons; Operational Anomalies 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...charging in the near geosynchronous orbit have been done. DeForest [4] investigated charging of ATS-5 satellite in geosynchronous orbit . He found that...common, high-level charging can also be experienced in low Earth orbit . Defense Meteorological Satellite Program (DMSP) spacecraft in low Earth polar

  11. Tropical sea surface temperatures and the earth's orbital eccentricity cycles

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.; Fernandes, A.A.; Mohan, R.

    cyclicities at ~100- and ~400-ka corresponding to the Earth's orbital eccentricity cycles. Results, therefore imply that the tropical Indian Ocean warm pool persisted during the Quaternary and the paleo-SSTs fluctuating at the orbital eccentricity frequencies...

  12. Earth view: A business guide to orbital remote sensing

    Science.gov (United States)

    Bishop, Peter C.

    1990-01-01

    The following subject areas are covered: Earth view - a guide to orbital remote sensing; current orbital remote sensing systems (LANDSAT, SPOT image, MOS-1, Soviet remote sensing systems); remote sensing satellite; and remote sensing organizations.

  13. Detection of Several Daemon Populations in Earth-Crossing Orbits

    Science.gov (United States)

    Drobyshevski, E. M.; Beloborodyy, M. V.; Kurakin, R. O.; Latypov, V. G.; Pelepelin, K. A.

    2003-01-01

    Experiments on scintillator-based detection of negative dark electric matter objects, daemons, representing Planckian supermassive (about 2x10 -5 g) particles that were detected in March 2000 as populating near-Earth, almost circular heliocentric orbits (NEACHOs), are being continued. The NEACHO objects hit the Earth with a velocity of about 10-15 km s-1. The results of these and new experiments (April-June 2001) are now being processed, taking into account the difference in scintillation signal shape depending on the magnitude and sign of the velocity of the daemons crossing our detector, which was purposefully made asymmetric with respect to the up-down direction of flight. The data accumulated during the experiment and processed in this way also reveal the presence of, firstly, a high-velocity (about 35-50 km s-1) daemon population whose objects can be related to a population in the Galactic disc and/or that in strongly elongated Earth-crossing heliocentric orbits and, secondly, a low-velocity (about 3-10 km s-1) population in geocentric Earth-surface-crossing orbits whose objects (GESCOs) traverse repeatedly the Earth, suffering a decrease in velocity by about 30-40% month in the process. The evolutionary relation between all these three (four?) populations is discussed. Conjectures concerning their manifestations in further observations are put forward. An analysis of possible interaction processes of daemons, which may have different velocities and directions of motion, with the detector components (ZnS(Ag) scintillator layers, tinned-iron sheets 0.3 mm thick, etc.) on the atomic (emission of Auger electrons) and nuclear (nucleon evaporation from a nucleus excited in the capture and, subsequently, the decay of its protons) levels has permitted estimation of some characteristic times. In particular, the decay time of a daemon-containing proton was found to be about 1 μs.

  14. Orbit Determination of Spacecraft in Earth-Moon L1 and L2 Libration Point Orbits

    Science.gov (United States)

    Woodard, Mark; Cosgrove, Daniel; Morinelli, Patrick; Marchese, Jeff; Owens, Brandon; Folta, David

    2011-01-01

    measurements that would be needed to meet the required orbit determination accuracies. Analysts used the Orbit Determination Error Analysis System (ODEAS) to perform covariance analyses using various tracking data schedules. From this analysis, it was determined that 3.5 hours of DSN TRK-2-34 range and Doppler tracking data every other day would suffice to meet the predictive orbit knowledge accuracies in the Lissajous region. The results of this analysis are presented. Both GTDS and ODTK have high-fidelity environmental orbit force models that allow for very accurate orbit estimation in the lunar Lissajous regime. These models include solar radiation pressure, Earth and Moon gravity models, third body gravitational effects from the Sun, and to a lesser extent third body gravitational effects from Jupiter, Venus, Saturn, and Mars. Increased position and velocity uncertainties following each maneuver, due to small execution performance errors, requires that several days of post-maneuver tracking data be processed to converge on an accurate post-maneuver orbit solution. The effects of maneuvers on orbit determination accuracy will be presented, including a comparison of the batch least squares technique to the extended Kalman filter/smoother technique. We will present the maneuver calibration results derived from processing post-maneuver tracking data. A dominant error in the orbit estimation process is the uncertainty in solar radiation pressure and the resultant force on the spacecraft. An estimation of this value can include many related factors, such as the uncertainty in spacecraft reflectivity and surface area which is a function of spacecraft orientation (spin-axis attitude), uncertainty in spacecraft wet mass, and potential seasonal variability due to the changing direction of the Sun line relative to the Earth-Moon Lissajous reference frame. In addition, each spacecraft occasionally enters into Earth or Moon penumbra or umbra and these shadow crossings reduche solar

  15. Earth-like aqueous debris-flow activity on Mars at high orbital obliquity in the last million years

    NARCIS (Netherlands)

    De Haas, T.; Hauber, E.; Conway, S.J.; Van Steijn, H.; Johnsson, A.; Kleinhans, M.G.

    2015-01-01

    Liquid water is currently extremely rare on Mars, but was more abundant during periods of high obliquity in the last few millions of years. This is testified by the widespread occurrence of mid-latitude gullies: small catchment-fan systems. However, there are no direct estimates of the amount and

  16. A Comparison of Damaging Meteoroid and Orbital Debris Fluxes in Earth Orbit

    Science.gov (United States)

    Cooke, William; Matney, Mark; Moorhead, Althea V.; Vavrin, Andrew

    2017-01-01

    Low Earth orbit is populated with a substantial amount of orbital debris, and it is usually assumed that the flux from these objects contributes to most of the hypervelocity particle risk to spacecraft in this region. The meteoroid flux is known to be dominant at very low altitudes (less than 300 km), where atmospheric drag rapidly removes debris, and at very high altitudes (beyond geostationary), where debris is practically non-existent. The vagueness of these boundaries and repeated questions from spacecraft projects have prompted this work, in which we compare the fluxes of meteoroids and orbital debris capable of producing a millimeter-deep crater in aluminum for circular orbits with altitudes ranging from the top of the atmosphere to 100,000 km. The outputs from the latest NASA debris and meteoroid models, ORDEM 3.0 and MEMR2, are combined with the modified Cour-Palais ballistic limit equation to make a realistic evaluation of the damage-capable particle fluxes, thereby establishing the relative contributions of hazardous debris and meteoroids throughout near-Earth space.

  17. Orbital debris and near-Earth environmental management: A chronology

    Science.gov (United States)

    Portree, David S. F.; Loftus, Joseph P., Jr.

    1993-12-01

    This chronology covers the 32-year history of orbital debris and near-Earth environmental concerns. It tracks near-Earth environmental hazard creation, research, observation, experimentation, management, mitigation, protection, and policy-making, with emphasis on the orbital debris problem. Included are the Project West Ford experiments; Soviet ASAT tests and U.S. Delta upper stage explosions; the Ariane V16 explosion, U.N. treaties pertinent to near-Earth environmental problems, the PARCS tests; space nuclear power issues, the SPS/orbital debris link; Space Shuttle and space station orbital debris issues; the Solwind ASAT test; milestones in theory and modeling the Cosmos 954, Salyut 7, and Skylab reentries; the orbital debris/meteoroid research link; detection system development; orbital debris shielding development; popular culture and orbital debris; Solar Max results; LDEF results; orbital debris issues peculiar to geosynchronous orbit, including reboost policies and the stable plane; seminal papers, reports, and studies; the increasing effects of space activities on astronomy; and growing international awareness of the near-Earth environment.

  18. Are artificial satellites orbits influenced by an expanding Earth?

    Directory of Open Access Journals (Sweden)

    G. Scalera

    2006-06-01

    Full Text Available Albeit in the past great theoretical and experimental efforts were made in proposing and searching for G time-decreasing, a major role could be played by an increase of M. A recent analysis (Scalera, 2003a converges toward an upper limit of the Earth’s mass variation in the order of magnitude of M/M=10-9 /yr. It is here discussed the possible role that can be played by parameters linked to the expanding Earth in the effects we observe in the orbital motion of the artificial satellites. The important result in this short note is the discrimination between the reality of the glacial rebound process and/or the relaxation of the 100m excess of equatorial bulge testified by the high rate of j2 , and the improbable role that glacial rebound can have in driving PM and TPW. It is recommended that the new technology of drag-free satellites be used (Gravity-Probe B is the first step to reveal possible residual orbital parameter variations ascribable to formerly unrecognized fictitious drag terms due to Earth radial increase.

  19. Equilibrium Temperature of a Satellite in LowEarth Orbit

    Directory of Open Access Journals (Sweden)

    T. M. Hegab

    2015-01-01

    Full Text Available The efficiency of artificial satellite equipment, essentially, depends on its temperature condition, which in the case of low-Earth orbit varies quite widely. The satellite temperature changes because of the fact that along with a portion of the orbit where the satellite perceives heat flows, caused by solar radiation directly incident on its surface and solar radiation, reflected from the Earth's surface; in general cases of the low earth orbit there is its shaded portion where the satellite receives only a relatively low intensive self-radiation of the Earth. The level of possible values of satellite temperature at different portions of low earth orbit can be estimated by the equilibrium temperature determined from the balance equation of heat flows, perceived and radiated by its surface.The analysis of heat flows, which act on the surface of an artificial satellite of conditional spherical shape, allows us to obtain the dependences, in order to find a satellite equilibrium temperature at different heights of its position above Earth's surface and an angle between the directions from the center of the Earth towards the Sun, and the satellite as it moves out of the shadow of the Earth and at different height of its position at the shaded portion of the orbit as well. These dependencies are used for graphing to show the changes of the equilibrium temperature of the low-Earth orbiting satellite.The presented technique allows us to evaluate the possible range of temperature change of the low-Earth orbiting satellite.

  20. Autonomous On-Board Optical Navigation Beyond Earth Orbit Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To date, navigation solutions are created by ground systems teams and then uploaded to vehicles operating beyond Earth orbit. However with the improvement of...

  1. Applications of low-earth-orbit power transmission

    Energy Technology Data Exchange (ETDEWEB)

    Arndt, G.D.; Kerwin, E.M.

    1986-01-01

    The use of low-earth-orbit transmission systems to transfer power between two co-orbiting satellites is investigated. A microwave system with a 20 m antenna and 30 m rectenna over a 5-10 km operating range could have possible applications for transmitting 100 kW of power. Antenna/rectenna trade-off sizings, taper analyses, orbital considerations, and possible uses are discussed.

  2. Near Earth Asteroids- Prospection, Orbit Modification and Mining

    Science.gov (United States)

    Grandl, W.; Bazso, A.

    2014-04-01

    The number of known Near Earth Asteroids (NEAs) has increased continuously during the last decades. Now we understand the role of asteroid impacts for the evolution of life on Earth. To ensure that mankind will survive in the long run, we have to face the "asteroid threat" seriously. On one hand we will have to develop methods of detection and deflection for Hazardous Asteroids, on the other hand we can use these methods to modify their orbits and exploit their resources. Rare-earth elements, rare metals like platinum group elements, etc. may be extracted more easily from NEAs than from terrestrial soil, without environmental pollution or political and social problems. In a first step NEAs, which are expected to contain resources like nickel-iron, platinum group metals or rare-earth elements, will be prospected by robotic probes. Then a number of asteroids with a minimum bulk density of 2 g/cm^3 and a diameter of 150 to 500 m will be selected for mining. Given the long duration of an individual mission time of 10-20 years, the authors propose a "pipeline" concept. While the observation of NEAs can be done in parallel, the precursor missions of the the next phase can be launched in short intervals, giving time for technical corrections and upgrades. In this way a continuous data flow is established and there are no idle times. For our purpose Potentially Hazardous Asteroids (PHAs) seem to be a favorable choice for the following reasons: They have frequent closeencounters to Earth, their minimum orbit intersection distance is less than 0.05 AU (Astronomic Units) and they have diameters exceeding 150 meters. The necessary velocity change (delta V) for a spaceship is below 12 km/s to reach the PHA. The authors propose to modify the orbits of the chosen PHAs by orbital maneuvers from solar orbits to stable Earth orbits beyond the Moon. To change the orbits of these celestial bodies it is necessary to develop advanced propulsion systems. They must be able to deliver high

  3. Space tourism: from earth orbit to the moon

    Science.gov (United States)

    Collins, P.

    Travel to and from the lunar surface has been known to be feasible since it was first achieved 34 years ago. Since that time there has been enormous progress in related engineering fields such as rocket propulsion, materials and avionics, and about 1 billion has been spent on lunar science and engineering research. Consequently there are no fundamental technical problems facing the development of lunar tourism - only business and investment problems. The outstanding problem is to reduce the cost of launch to low Earth orbit. Recently there has been major progress towards overturning the myth that launch costs are high because of physical limits. Several "X Prize" competitor vehicles currently in test-flight are expected to be able to perform sub-orbital flights at approximately 1/1,000 of the cost of Alan Shepard's similar flight in 1961. This activity could have started 30 years ago if space agencies had had economic rather than political objectives. A further encouraging factor is that the demand for space tourism seems potentially limitless. Starting with sub-orbital flights and growing through orbital activities, travel to the Moon will offer further unique attractions. In every human culture there is immense interest in the Moon arising from millennia of myths. In addition, bird-like flying sports, first described by Robert Heinlein, will become another powerful demand factor. Roundtrips of 1 to 2 weeks are very convenient for travel companies; and the radiation environment will permit visitors several days of surface activity without significant health risks. The paper also discusses economic aspects of lunar tourism, including the benefits it will have for those on Earth. Lunar economic development based on tourism will have much in common with economic development on Earth based on tourism: starting from the fact that many people spontaneously wish to visit popular places, companies in the tourism industry invest to sell a growing range of services to ever

  4. Enhancing the kinematic precise orbit determination of low earth orbiters using GPS receiver clock modelling

    Science.gov (United States)

    Yang, Yang; Yue, Xiaokui; Yuan, Jianping; Rizos, Chris

    2014-11-01

    Clock error estimation has been the focus of a great deal of research because of the extensive usage of clocks in GPS positioning applications. The receiver clock error in the spacecraft orbit determination is commonly estimated on an epoch-by-epoch basis, along with the spacecraft’s position. However, due to the high correlation between the spacecraft orbit altitude and the receiver clock parameters, estimates of the radial component are degraded in the kinematic approach. Using clocks with high stability, the predictable behaviour of the receiver oscillator can be exploited to improve the positioning accuracy, especially for the radial component. This paper introduces two GPS receiver clock models to describe the deterministic and stochastic property of the receiver clock, both of which can improve the accuracy of kinematic orbit determination for spacecraft in low earth orbit. In particular, the clock parameters are estimated as time offset and frequency offset in the two-state model. The frequency drift is also estimated as an unknown parameter in the three-state model. Additionally, residual non-deterministic random errors such as frequency white noise, frequency random walk noise and frequency random run noise are modelled. Test results indicate that the positioning accuracy could be improved significantly using one day of GRACE flight data. In particular, the error of the radial component was reduced by over 40.0% in the real-time scenario.

  5. Numerical orbit generators of artificial earth satellites

    Science.gov (United States)

    Kugar, H. K.; Dasilva, W. C. C.

    1984-04-01

    A numerical orbit integrator containing updatings and improvements relative to the previous ones that are being utilized by the Departmento de Mecanica Espacial e Controle (DMC), of INPE, besides incorporating newer modellings resulting from the skill acquired along the time is presented. Flexibility and modularity were taken into account in order to allow future extensions and modifications. Characteristics of numerical accuracy, processing quickness, memory saving as well as utilization aspects were also considered. User's handbook, whole program listing and qualitative analysis of accuracy, processing time and orbit perturbation effects were included as well.

  6. An Earth-mass planet orbiting α Centauri B.

    Science.gov (United States)

    Dumusque, Xavier; Pepe, Francesco; Lovis, Christophe; Ségransan, Damien; Sahlmann, Johannes; Benz, Willy; Bouchy, François; Mayor, Michel; Queloz, Didier; Santos, Nuno; Udry, Stéphane

    2012-11-08

    Exoplanets down to the size of Earth have been found, but not in the habitable zone--that is, at a distance from the parent star at which water, if present, would be liquid. There are planets in the habitable zone of stars cooler than our Sun, but for reasons such as tidal locking and strong stellar activity, they are unlikely to harbour water-carbon life as we know it. The detection of a habitable Earth-mass planet orbiting a star similar to our Sun is extremely difficult, because such a signal is overwhelmed by stellar perturbations. Here we report the detection of an Earth-mass planet orbiting our neighbour star α Centauri B, a member of the closest stellar system to the Sun. The planet has an orbital period of 3.236 days and is about 0.04 astronomical units from the star (one astronomical unit is the Earth-Sun distance).

  7. Investigation of Malaysian Low Earth Orbits for Remote Sensing Applications

    Science.gov (United States)

    Okasha, M.; Shuib, I.; Idres, M.

    2017-03-01

    This paper explores the orbit design procedures of a low Earth satellite orbit for remote sensing mission. The mission objective is to gather images over Malaysia as an area of interest for a variety of applications such as land monitoring and digital mapping. The design procedures are mainly driven by the payload performance, lighting conditions and the coverage requirements. Standard CubeSat platform with a NanoCam is considered for the mission. Numerical investigations show the trade studies of various satellite orbital parameters and their impact on the performance. The orbital parameters are optimized to meet the mission design requirements.

  8. 3D Orbit Visualization for Earth-Observing Missions

    Science.gov (United States)

    Jacob, Joseph C.; Plesea, Lucian; Chafin, Brian G.; Weiss, Barry H.

    2011-01-01

    This software visualizes orbit paths for the Orbiting Carbon Observatory (OCO), but was designed to be general and applicable to any Earth-observing mission. The software uses the Google Earth user interface to provide a visual mechanism to explore spacecraft orbit paths, ground footprint locations, and local cloud cover conditions. In addition, a drill-down capability allows for users to point and click on a particular observation frame to pop up ancillary information such as data product filenames and directory paths, latitude, longitude, time stamp, column-average dry air mole fraction of carbon dioxide, and solar zenith angle. This software can be integrated with the ground data system for any Earth-observing mission to automatically generate daily orbit path data products in Google Earth KML format. These KML data products can be directly loaded into the Google Earth application for interactive 3D visualization of the orbit paths for each mission day. Each time the application runs, the daily orbit paths are encapsulated in a KML file for each mission day since the last time the application ran. Alternatively, the daily KML for a specified mission day may be generated. The application automatically extracts the spacecraft position and ground footprint geometry as a function of time from a daily Level 1B data product created and archived by the mission s ground data system software. In addition, ancillary data, such as the column-averaged dry air mole fraction of carbon dioxide and solar zenith angle, are automatically extracted from a Level 2 mission data product. Zoom, pan, and rotate capability are provided through the standard Google Earth interface. Cloud cover is indicated with an image layer from the MODIS (Moderate Resolution Imaging Spectroradiometer) aboard the Aqua satellite, which is automatically retrieved from JPL s OnEarth Web service.

  9. Three-Dimensional Orbits of Earth Satellites, Including Effects of Earth Oblateness and Atmospheric Rotation

    Science.gov (United States)

    Nielsen, Jack N.; Goodwin, Frederick K.; Mersman, William A.

    1958-01-01

    The principal purpose of the present paper is to present sets of equations which may be used for calculating complete trajectories of earth satellites from outer space to the ground under the influence of air drag and gravity, including oblateness effects, and to apply these to several examples of entry trajectories starting from a circular orbit. Equations of motion, based on an "instantaneous ellipse" technique, with polar angle as independent variable, were found suitable for automatic computation of orbits in which the trajectory consists of a number of revolutions. This method is suitable as long as the trajectory does not become nearly vertical. In the terminal phase of the trajectories, which are nearly vertical, equations of motion in spherical polar coordinates with time as the independent variable were found to be more suitable. In the first illustrative example the effects of the oblateness component of the earth's gravitational field and of atmospheric rotation were studied for equatorial orbits. The satellites were launched into circular orbits at a height of 120 miles, an altitude sufficiently high that a number of revolutions could be studied. The importance of the oblateness component of the earth's gravitational field is shown by the fact that a satellite launched at circular orbital speed, neglecting oblateness, has a perigee some 67,000 feet lower when oblateness forces are included in the equations of motion than when they are not included. Also, the loss in altitude per revolution is double that of a satellite following an orbit not subject to oblateness. The effect of atmospheric rotation on the loss of altitude per revolution was small. As might be surmised, the regression of the line of nodes as predicted by celestial mechanics is unchanged when drag is included. It is clear that the inclination of the orbital plane to the equator will be relatively unaffected by drag for no atmospheric rotation since the drag lies in the orbital plane in

  10. GALILEO ORBITER EARTH POS EARTH2 FLYBY TRAJ V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter 60 second sampled trajectory data from the Earth-2 flyby in GSE and GSM coordinates. These data cover the interval 1992-11-03 to 1992-12-20.

  11. GALILEO ORBITER EARTH POS EARTH1 FLYBY TRAJ V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter 60 second sampled trajectory data from the Earth-1 flyby in GSE and GSM coordinates. These data cover the interval 1990-11-05 to 1990-12-31.

  12. GALILEO ORBITER EARTH MAG SUMM EARTH1 SUMMARY V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated 20 second averaged data from the Earth-1 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...

  13. GALILEO ORBITER EARTH MAG SUMM EARTH2 SUMMARY V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated 20 second averaged data from the Earth-2 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...

  14. High Power Orbit Transfer Vehicle

    National Research Council Canada - National Science Library

    Gulczinski, Frank

    2003-01-01

    ... from Virginia Tech University and Aerophysics, Inc. to examine propulsion requirements for a high-power orbit transfer vehicle using thin-film voltaic solar array technologies under development by the Space Vehicles Directorate (dubbed PowerSail...

  15. Spacecraft Orbits for Earth/Mars-Lander Radio Relay

    Science.gov (United States)

    Noreen, Gary; Diehl, Roger; Neelon, Joseph

    2004-01-01

    A report discusses a network of spacecraft, in orbit around Mars, used to relay radio communications between Earth stations and mobile exploratory robots (rovers) as well as stationary scientific instruments that have been landed on the Mars surface. The relay spacecraft include two already in orbit plus several others planned to arrive at Mars in the years 2004 through 2008. A major portion of the report is devoted to the orbit of the G. Macroni Orbiter, which is in the midst of an iterative design process and is intended to be the first Mars orbiter designed primarily for radio relay. Candidate orbits are analyzed with a view toward choosing one that maximizes the amount of time available for communication with surface units, taking account of visibility as a function of position, the limit on communication distance at low power, and the fact that surface units can transmit more easily when they are in sunlight. Two promising new orbits for Mars relay satellites are identified: a 1/2-sol apoapsis-at-constant-time-of-day equatorial orbit and a 1/4-sol apoapsis-at-constant-time-of-day, critical-inclination orbit.

  16. Near-Earth Object Survey Orbit Quality Analysis

    Science.gov (United States)

    Buie, Marc W.

    2013-05-01

    Abstract (2,250 Maximum Characters): The Sentinel Mission is currently under development by the B612 Foundation and Ball Aerospace. The mission concept is based on a space-based infrared telescope in an independent orbit similar to that of Venus. Being in an orbit interior to the Earth greatly reduces the time to complete the survey of the near-Earth region compared to a similar survey that could be accomplished from ground-based or orbiting observatory near the Earth. One of the key mission design elements is the cadence of observation. This involves the tiling pattern for how the instrument field-of-view maps out the sky and the repeat interval between successive observations. This presentation will show a quantitative analysis of orbit determination from this type of platform and show how the expected distribution of NEOs will be observed and the orbit qualities that will result. From this analysis, limits can then be placed on the degree of confusion that the cadence can tolerate before linking different epochs becomes problematic.

  17. Earth-Mars transfers through Moon Distant Retrograde Orbits

    Science.gov (United States)

    Conte, Davide; Di Carlo, Marilena; Ho, Koki; Spencer, David B.; Vasile, Massimiliano

    2018-02-01

    This paper focuses on the trajectory design which is relevant for missions that would exploit the use of asteroid mining in stable cis-lunar orbits to facilitate deep space missions, specifically human Mars exploration. Assuming that a refueling "gas station" is present at a given lunar Distant Retrograde Orbit (DRO), ways of departing from the Earth to Mars via that DRO are analyzed. Thus, the analysis and results presented in this paper add a new cis-lunar departure orbit for Earth-Mars missions. Porkchop plots depicting the required C3 at launch, v∞ at arrival, Time of Flight (TOF), and total Δ V for various DRO departure and Mars arrival dates are created and compared with results obtained for low Δ V Low Earth Orbit (LEO) to Mars trajectories. The results show that propellant-optimal trajectories from LEO to Mars through a DRO have higher overall mission Δ V due to the additional stop at the DRO. However, they have lower Initial Mass in LEO (IMLEO) and thus lower gear ratio as well as lower TOF than direct LEO to Mars transfers. This results in a lower overall spacecraft dry mass that needs to be launched into space from Earth's surface.

  18. A Geostationary Earth Orbit Satellite Model Using Easy Java Simulation

    Science.gov (United States)

    Wee, Loo Kang; Goh, Giam Hwee

    2013-01-01

    We develop an Easy Java Simulation (EJS) model for students to visualize geostationary orbits near Earth, modelled using a Java 3D implementation of the EJS 3D library. The simplified physics model is described and simulated using a simple constant angular velocity equation. We discuss four computer model design ideas: (1) a simple and realistic…

  19. Precise halo orbit design and optimal transfer to halo orbits from earth using differential evolution

    Science.gov (United States)

    Nath, Pranav; Ramanan, R. V.

    2016-01-01

    The mission design to a halo orbit around the libration points from Earth involves two important steps. In the first step, we design a halo orbit for a specified size and in the second step, we obtain an optimal transfer trajectory design to the halo orbit from an Earth parking orbit. Conventionally, the preliminary design for these steps is obtained using higher order analytical solution and the dynamical systems theory respectively. Refinements of the design are carried out using gradient based methods such as differential correction and pseudo arc length continuation method under the of circular restricted three body model. In this paper, alternative single level schemes are developed for both of these steps based on differential evolution, an evolutionary optimization technique. The differential evolution based scheme for halo orbit design produces precise halo orbit design avoiding the refinement steps. Further, in this approach, prior knowledge of higher order analytical solutions for the halo orbit design is not needed. The differential evolution based scheme for the transfer trajectory, identifies the precise location on the halo orbit that needs minimum energy for insertion and avoids exploration of multiple points. The need of a close guess is removed because the present scheme operates on a set of bounds for the unknowns. The constraint on the closest approach altitude from Earth is handled through objective function. The use of these schemes as the design and analysis tools within the of circular restricted three body model is demonstrated through case studies for missions to the first libration point of Sun-Earth system.

  20. Dynamics of Orbits near 3:1 Resonance in the Earth-Moon System

    Science.gov (United States)

    Dichmann, Donald J.; Lebois, Ryan; Carrico, John P., Jr.

    2013-01-01

    The Interstellar Boundary Explorer (IBEX) spacecraft is currently in a highly elliptical orbit around Earth with a period near 3:1 resonance with the Moon. Its orbit is oriented so that apogee does not approach the Moon. Simulations show this orbit to be remarkably stable over the next twenty years. This article examines the dynamics of such orbits in the Circular Restricted 3-Body Problem (CR3BP). We look at three types of periodic orbits, each exhibiting a type of symmetry of the CR3BP. For each of the orbit types, we assess the local stability using Floquet analysis. Although not all of the periodic solutions are stable in the mathematical sense, any divergence is so slow as to produce practical stability over several decades. We use Poincare maps with twenty-year propagations to assess the nonlinear stability of the orbits, where the perturbation magnitudes are related to the orbit uncertainty for the IBEX mission. Finally we show that these orbits belong to a family of orbits connected in a bifurcation diagram that exhibits exchange of stability. The analysis of these families of period orbits provides a valuable starting point for a mission orbit trade study.

  1. Size Dependence of Dust Distribution around the Earth Orbit

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Takahiro; Takeuchi, Taku [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551 (Japan); Kobayashi, Hiroshi; Ishihara, Daisuke; Kondo, Toru; Kaneda, Hidehiro, E-mail: t.ueda@geo.titech.ac.jp [Graduate School of Science, Nagoya University, Nagoya, Aichi, 464-8602 (Japan)

    2017-05-01

    In the solar system, interplanetary dust particles (IDPs) originating mainly from asteroid collisions and cometary activities drift to Earth orbit due to Poynting–Robertson drag. We analyzed the thermal emission from IDPs that was observed by the first Japanese infrared astronomical satellite, AKARI . The observed surface brightness in the trailing direction of the Earth orbit is 3.7% greater than that in the leading direction in the 9 μ m band and 3.0% in the 18 μ m band. In order to reveal dust properties causing leading–trailing surface brightness asymmetry, we numerically integrated orbits of the Sun, the Earth, and a dust particle as a restricted three-body problem including radiation from the Sun. The initial orbits of particles are determined according to the orbits of main-belt asteroids or Jupiter-family comets. Orbital trapping in mean motion resonances results in a significant leading–trailing asymmetry so that intermediate sized dust (∼10–100 μ m) produces a greater asymmetry than zodiacal light. The leading–trailing surface brightness difference integrated over the size distribution of the asteroidal dust is obtained to be 27.7% and 25.3% in the 9 μ m and 18 μ m bands, respectively. In contrast, the brightness difference for cometary dust is calculated as 3.6% and 3.1% in the 9 μ m and 18 μ m bands, respectively, if the maximum dust radius is set to be s {sub max} = 3000 μ m. Taking into account these values and their errors, we conclude that the contribution of asteroidal dust to the zodiacal infrared emission is less than ∼10%, while cometary dust of the order of 1 mm mainly accounts for the zodiacal light in infrared.

  2. Laboratory investigations: Low Earth orbit environment chemistry with spacecraft surfaces

    Science.gov (United States)

    Cross, Jon B.

    1990-01-01

    Long-term space operations that require exposure of material to the low earth orbit (LEO) environment must take into account the effects of this highly oxidative atmosphere on material properties and the possible contamination of the spacecraft surroundings. Ground-based laboratory experiments at Los Alamos using a newly developed hyperthermal atomic oxygen (AO) source have shown that not only are hydrocarbon based materials effected but that inorganic materials such as MoS2 are also oxidized and that thin protective coatings such as Al2O3 can be breached, producing oxidation of the underlying substrate material. Gas-phase reaction products, such as SO2 from oxidation of MoS2 and CO and CO2 from hydrocarbon materials, have been detected and have consequences in terms of spacecraft contamination. Energy loss through gas-surface collisions causing spacecraft drag has been measured for a few select surfaces and has been found to be highly dependent on the surface reactivity.

  3. Spectral properties of near-Earth asteroids on cometary orbits

    Science.gov (United States)

    Popescu, M.; Vaduvescu, O.; de Leon, J.; Boaca, I. L.; Gherase, R. M.; Nedelcu, D. A.; INT students, I. N. G.

    2017-09-01

    We studied the spectral distributions of near-Earth asteroids on cometary orbits (NEACOs) in order to identify potential dormant or extinct comets among these objects. We present the spectral observations for 19 NEACOs obtained with Isaac Newton Telescope and Infrared Telescope Facility (IRTF). Although initially classified as asteroid, one of our targets - 2007 VA85 was confirmed to be active comet 333P/LINEAR on its 2016 appearance. We found that the NEACOs population is a mixing of different compositional classes.

  4. Efficiency in Carrying Cargo to Earth Orbits: Spaceports Repositioning

    Directory of Open Access Journals (Sweden)

    Jakub Hospodka

    2016-10-01

    Full Text Available Space flights are in these days not any more question of technology, but more question of costs. One way how to decrease cost of launch is change of home spaceport. Change of home spaceport for different rockets is a way to achieve more efficient launches to space. The reason is different acceleration achieved from Earth rotation. We added several mathematical calculations of missions to Low Earth Orbit and Geostationary Earth Orbit to show bonuses from Earth rotation and effect of atmospheric drag on specific rockets used these days. We discussed only already used space vessels. Namely Arianne 5, Delta 4 heavy, Proton-M, Zenit and Falcon9. For reaching GEO we discuss possibility of using Hohmman transfer, because none of aforementioned vessels is available for direct GEO entry. As possible place for launch we discussed spaceports Baikonur, Kennedy Space center, Guyana Space center and Sea Launch platform. We present results in form of additional acceleration for each spaceport, and we also project this additional acceleration in means payload increase. In conclusion we find important differences between vessel effectivity based on spaceport used for launch. Change of launch location may bring significant cost decrease for operators.

  5. Assessing the Impact of Earth Radiation Pressure Acceleration on Low-Earth Orbit Satellites

    Science.gov (United States)

    Vielberg, Kristin; Forootan, Ehsan; Lück, Christina; Kusche, Jürgen; Börger, Klaus

    2017-04-01

    The orbits of satellites are influenced by several external forces. The main non-gravitational forces besides thermospheric drag, acting on the surface of satellites, are accelerations due to the Earth and Solar Radiation Pres- sure (SRP and ERP, respectively). The sun radiates visible and infrared light reaching the satellite directly, which causes the SRP. Earth also emits and reflects the sunlight back into space, where it acts on satellites. This is known as ERP acceleration. The influence of ERP increases with decreasing distance to the Earth, and for low-earth orbit (LEO) satellites ERP must be taken into account in orbit and gravity computations. Estimating acceler- ations requires knowledge about energy emitted from the Earth, which can be derived from satellite remote sensing data, and also by considering the shape and surface material of a satellite. In this sensitivity study, we assess ERP accelerations based on different input albedo and emission fields and their modelling for the satellite missions Challenging Mini-Satellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE). As input fields, monthly 1°x1° products of Clouds and the Earth's Radiant En- ergy System (CERES), L3 are considered. Albedo and emission models are generated as latitude-dependent, as well as in terms of spherical harmonics. The impact of different albedo and emission models as well as the macro model and the altitude of satellites on ERP accelerations will be discussed.

  6. Radiation Dose Analysis of Galactic Cosmic Ray in Low Earth Orbit/Near Equatorial Orbit

    Science.gov (United States)

    Suparta, W.; Zulkeple, S. K.

    2014-10-01

    Space environment contained harmful radiation that posed risk to spacecraft orbiting the Earth. In this paper, we looked into radiation doses caused by galactic cosmic ray (GCR) towards satellites orbiting in low earth orbit (LEO) near Earth's equator (NEqO) and compared them with doses caused by solar energetic particles (SEP) and trapped particles to determine the damage level of GCR. The radiation doses included linear energy transfer (LET) and nonionizing energy loss (NIEL) through a 1mm gallium arsenide (GaAs) planar geometry by using Space Environment Information System (SPENVIS) method. The orbital data followed Malaysian Razaksat satellite at 685km altitude and 9° inclination during selected solar minimum and solar maximum from solar cycles 21 to 24. We found that trapped particles gave the highest LET and no SEP was detected in SPENVIS. The LET values tend to be higher during solar minimum for trapped particles and GCR, corresponding to their anti-correlated fluxes with the solar activity. However, the NIEL values for GCR in solar cycle 23 did not follow the anti-correlation pattern.

  7. Plasma Flowfields Around Low Earth Orbit Objects: Aerodynamics to Underpin Orbit Predictions

    Science.gov (United States)

    Capon, Christopher; Boyce, Russell; Brown, Melrose

    2016-07-01

    Interactions between orbiting bodies and the charged space environment are complex. The large variation in passive body parameters e.g. size, geometry and materials, makes the plasma-body interaction in Low Earth Orbit (LEO) a region rich in fundamental physical phenomena. The aerodynamic interaction of LEO orbiting bodies with the neutral environment constitutes the largest non-conservative force on the body. However in general, study of the LEO plasma-body interaction has not been concerned with external flow physics, but rather with the effects on surface charging. The impact of ionospheric flow physics on the forces on space debris (and active objects) is not well understood. The work presented here investigates the contribution that plasma-body interactions have on the flow structure and hence on the total atmospheric force vector experienced by a polar orbiting LEO body. This work applies a hybrid Particle-in-Cell (PIC) - Direct Simulation Monte Carlo (DSMC) code, pdFoam, to self-consistently model the electrostatic flowfield about a cylinder with a uniform, fixed surface potential. Flow conditions are representative of the mean conditions experienced by the Earth Observing Satellite (EOS) based on the International Reference Ionosphere model (IRI-86). The electron distribution function is represented by a non-linear Boltzmann electron fluid and ion gas-surface interactions are assumed to be that of a neutralising, conducting, thermally accommodating solid wall with diffuse reflections. The variation in flowfield and aerodynamic properties with surface potential at a fixed flow condition is investigated, and insight into the relative contributions of charged and neutral species to the flow physics experienced by a LEO orbiting body is provided. This in turn is intended to help improve the fidelity of physics-based orbit predictions for space debris and other near-Earth space objects.

  8. Nickel hydrogen low Earth orbit test program update and status

    Science.gov (United States)

    Badcock, C. C.; Donley, S. W.; Felts, A. B.; Haag, R. L.

    1987-01-01

    The current status of nickel-hydrogen (NiH2) testing ongong at NWSC, Crane In, and The Aerospace Corporation, El Segundo, Ca are described. The objective of this testing is to develop a database for NiH2 battery use in Low Earth Orbit (LEO) and support applications in Medium Altitude Orbit (MAO). Individual pressure vessel-type cells are being tested. A minimum of 200 cells (3.5 in diameter and 4.5 in diameter) are included in the test, from four U.S. vendors. As of this date (Nov. 18, 1986) approximately 60 cells have completed preliminary testing (acceptance, characterization, and environmental testing) and have gone into life cycling.

  9. Solar radiation pressure resonances in Low Earth Orbits

    Science.gov (United States)

    Alessi, Elisa Maria; Schettino, Giulia; Rossi, Alessandro; Valsecchi, Giovanni B.

    2018-01-01

    The aim of this work is to highlight the crucial role that orbital resonances associated with solar radiation pressure can have in Low Earth Orbit. We review the corresponding literature, and provide an analytical tool to estimate the maximum eccentricity which can be achieved for well-defined initial conditions. We then compare the results obtained with the simplified model with the results obtained with a more comprehensive dynamical model. The analysis has important implications both from a theoretical point of view, because it shows that the role of some resonances was underestimated in the past, and also from a practical point of view in the perspective of passive deorbiting solutions for satellites at the end-of-life.

  10. Materials resistance to low earth orbit environmental effects

    Science.gov (United States)

    Pippin, H. G.; Torre, L. P.; Linton, R. G.; Whitaker, A. F.

    1989-01-01

    A number of flexible polymeric materials have been considered as condidates for protective coatings on Kapton film. These coatings have been tested under a variety of environments, each of which simulates one or more aspects of the low earth orbit space environment. Mass loss rates vs fluence and temperatue, optical properties, and surface characteristics under exposure to the various environments will be presented. Kinetics data on Kapton and other materials is interpreted in terms of bond strengths and relative thermodynamic stabilities of potential products. Activation energy for degradation of Kapton by oxygen atoms was determined to be 30 + or - 5 kJ/mol. Materials tested include silicones, fluorosilicones, fluorophosphazenes, fluorocarbons, and hydrocarbons.

  11. Two Earth-sized planets orbiting Kepler-20.

    Science.gov (United States)

    Fressin, Francois; Torres, Guillermo; Rowe, Jason F; Charbonneau, David; Rogers, Leslie A; Ballard, Sarah; Batalha, Natalie M; Borucki, William J; Bryson, Stephen T; Buchhave, Lars A; Ciardi, David R; Désert, Jean-Michel; Dressing, Courtney D; Fabrycky, Daniel C; Ford, Eric B; Gautier, Thomas N; Henze, Christopher E; Holman, Matthew J; Howard, Andrew; Howell, Steve B; Jenkins, Jon M; Koch, David G; Latham, David W; Lissauer, Jack J; Marcy, Geoffrey W; Quinn, Samuel N; Ragozzine, Darin; Sasselov, Dimitar D; Seager, Sara; Barclay, Thomas; Mullally, Fergal; Seader, Shawn E; Still, Martin; Twicken, Joseph D; Thompson, Susan E; Uddin, Kamal

    2011-12-20

    Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R(⊕)), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R(⊕)) and the other smaller than the Earth (0.87R(⊕)), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.

  12. An Earth Orbiting Satellite Service and Repair Facility

    Science.gov (United States)

    Berndt, Andrew; Cardoza, Mike; Chen, John; Daley, Gunter; Frizzell, Andy; Linton, Richard; Rast, Wayne

    1989-01-01

    A conceptual design was produced for the Geosynchronous Satellite Servicing Platform (GSSP), an orbital facility capable of repairing and servicing satellites in geosynchronous orbit. The GSSP is a man-tended platform, which consists of a habitation module, operations module, service bay and truss assembly. This design review includes an analysis of life support systems, thermal and power requirements, robotic and automated systems, control methods and navigation, and communications systems. The GSSP will utilize existing technology available at the time of construction, focusing mainly on modifying and integrating existing systems. The entire facility, along with two satellite retrieval vehicles (SRV), will be placed in geosynchronous orbit by the Advanced Launch System. The SRV will be used to ferry satellites to and from the GSSP. Technicians will be transferred from Earth to the GSSP and back in an Apollo-derived Crew Transfer Capsule (CTC). These missions will use advanced telerobotic equipment to inspect and service satellites. Four of these missions are tentatively scheduled per year. At this rate, the GSSP will service over 650 satelites during the projected 25 year lifespan.

  13. Degradation of Spacesuit Fabrics in Low Earth Orbit

    Science.gov (United States)

    Gaier, James R.; Baldwin, Sammantha M.; Folz, Angela D.; Waters, Deborah L.; McCue, Terry R.; Jaworske, Donald A.; Clark, Gregory W.; Rogers, Kerry J.; Batman, Brittany; Bruce, John; hide

    2012-01-01

    Six samples of pristine and dust-abraded outer layer spacesuit fabrics were included in the Materials International Space Station Experiment-7, in which they were exposed to the wake-side low Earth orbit environment on the International Space Station (ISS) for 18 months in order to determine whether abrasion by lunar dust increases radiation degradation. The fabric samples were characterized using optical microscopy, optical spectroscopy, field emission scanning electron microscopy, atomic force microscopy, and tensile testing before and after exposure on the ISS. Comparison of pre- and post-flight characterizations showed that the environment darkened and reddened all six fabrics, increasing their integrated solar absorptance by 7 to 38 percent. There was a decrease in the ultimate tensile strength and elongation to failure of lunar dust abraded Apollo spacesuit fibers by a factor of four and an increase in the elastic modulus by a factor of two.

  14. Optimization of Return Trajectories for Orbital Transfer Vehicle between Earth and Moon

    Science.gov (United States)

    Funase, Ryu; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

    2007-01-01

    In this paper, optimum trajectories in Earth Transfer Orbit (ETO) for a lunar transportation system are proposed. This paper aims at improving the payload ratio of the reusable orbital transfer vehicle (OTV), which transports the payload from Low Earth Orbit (LEO) to Lunar Low Orbit (LLO) and returns to LEO. In ETO, we discuss ballistic flight using chemical propulsion, multi-impulse flight using electrical propulsion, and aero-assisted flight using aero-brake. The feasibility of the OTV is considered.

  15. The Earth-Moon Transfer Trajectory Design and Analysis using Intermediate Loop Orbits

    Science.gov (United States)

    Song, Young-Joo; Woo, Jin; Park, Sang-Young; Kyu-Hong Choi; Sim, Eun-Sup

    2009-06-01

    Various Earth-Moon transfer trajectories are designed and analyzed to prepare the future Korea's Lunar missions. Minimum fuel trajectory solutions are obtained for the departure year of 2017, 2020, 2022, and every required mission phases are analyzed from Earth departure to the final lunar mission orbit. N-body equations of motion are formulated which include the gravitational effect of the Sun, Earth and Moon. In addition, accelerations due to geopotential harmonics, Lunar J2 and solar radiation pressures are considered. Impulsive high thrust is assumed as the main thrusting method of spacecraft with launcher capability of KSLV-2 which is planned to be developed. For the method of injecting a spacecraft into a trans Lunar trajectory, both direct shooting from circular parking orbit and shooting from the multiple elliptical intermediate orbits are adapted, and their design results are compared and analyzed. In addition, spacecraft's visibility from Deajeon ground station are constrained to see how they affect the magnitude of TLI (Trans Lunar Injection) maneuver. The results presented in this paper includes launch opportunities, required optimal maneuver characteristics for each mission phase as well as the trajectory characteristics and numerous related parameters. It is confirmed that the final mass of Korean lunar explorer strongly depends onto the initial parking orbit's altitude and launcher's capability, rather than mission start time.

  16. The Earth-Moon Transfer Trajectory Design and Analysis using Intermediate Loop Orbits

    Directory of Open Access Journals (Sweden)

    Young-Joo Song

    2009-06-01

    Full Text Available Various Earth-Moon transfer trajectories are designed and analyzed to prepare the future Korea's Lunar missions. Minimum fuel trajectory solutions are obtained for the departure year of 2017, 2020, 2022, and every required mission phases are analyzed from Earth departure to the final lunar mission orbit. N-body equations of motion are formulated which include the gravitational effect of the Sun, Earth and Moon. In addition, accelerations due to geopotential harmonics, Lunar J2 and solar radiation pressures are considered. Impulsive high thrust is assumed as the main thrusting method of spacecraft with launcher capability of KSLV-2 which is planned to be developed. For the method of injecting a spacecraft into a trans Lunar trajectory, both direct shooting from circular parking orbit and shooting from the multiple elliptical intermediate orbits are adapted, and their design results are compared and analyzed. In addition, spacecraft's visibility from Deajeon ground station are constrained to see how they affect the magnitude of TLI (Trans Lunar Injection maneuver. The results presented in this paper includes launch opportunities, required optimal maneuver characteristics for each mission phase as well as the trajectory characteristics and numerous related parameters. It is confirmed that the final mass of Korean lunar explorer strongly depends onto the initial parking orbit's altitude and launcher's capability, rather than mission start time.

  17. Controllable ON-OFF adhesion for Earth orbit grappling applications

    Science.gov (United States)

    Parness, Aaron; Hilgendorf, Tyler; Daniel, Phillip; Frost, Matt; White, Victor; Kennedy, Brett

    ON-OFF adhesives can benefit multiple Earth orbit applications by providing the capability to selectively anchor two surfaces together repeatedly and releasably without significant preload. Key to this new capability, targets will not need special preparation; ON-OFF adhesives can be used with cooperative and non-cooperative objects, like defunct satellites or space debris. Using an ON-OFF adhesive gripper allows large surfaces on a target to serve as potential grapple points, reducing the precision needed in the sensing and control throughout the grapple operation. A space-rated adhesive structure is presented that can be turned ON-OFF using a slight sliding motion. This adhesive mimics the geometry and performance characteristics of the adhesive structures found on the feet of gecko lizards. Results from adhesive testing on common orbital surfaces like solar panels, thermal blankets, composites, and painted surfaces are presented. Early environmental testing results from cold temperature and vacuum tests are also presented. Finally, the paper presents the design, fabrication, and preliminary testing of a gripping mechanism enabled by these ON-OFF adhesives in preparation for satellite-servicing applications. Adhesive levels range from near zero on rough surfaces to more than 75 kPa on smooth surfaces like glass.

  18. Innovations in mission architectures for exploration beyond low Earth orbit

    Science.gov (United States)

    Cooke, D. R.; Joosten, B. J.; Lo, M. W.; Ford, K. M.; Hansen, R. J.

    2003-01-01

    Through the application of advanced technologies and mission concepts, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to science driven; technology enabled human and robotic exploration. Numbers and masses of vehicles required are greatly reduced, yet the pursuit of a broader range of science objectives is enabled. The scope of human missions considered range from the assembly and maintenance of large aperture telescopes for emplacement at the Sun-Earth libration point L2, to human missions to asteroids, the moon and Mars. The vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities, which allows for future decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration. c2003 American Institute of Aeronautics and Astronautics. Published by Elsevier Science Ltd. All rights reserved.

  19. Lunar shadow eclipse prediction models for the Earth orbiting spacecraft: Comparison and application to LEO and GEO spacecrafts

    Science.gov (United States)

    Srivastava, Vineet K.; Kumar, Jai; Kulshrestha, Shivali; Srivastava, Ashutosh; Bhaskar, M. K.; Kushvah, Badam Singh; Shiggavi, Prakash; Vallado, David A.

    2015-05-01

    A solar eclipse occurs when the Sun, Moon and Earth are aligned in such a way that shadow of the Moon falls on the Earth. The Moon's shadow also falls on the Earth orbiting spacecraft. In this case, the alignment of the Sun, Moon, and spacecraft is similar to that of the Sun, Moon, and Earth but this phenomenon is often referred as a lunar eclipse falling on the spacecraft. Lunar eclipse is not as regular in terms of times of occurrence, duration, and depth as the Earth shadow eclipse and number of its occurrence per orbital location per year ranges from zero to four with an average of two per year; a spacecraft may experience two to three lunar eclipses within a twenty-four hour period [2]. These lunar eclipses can cause severe spacecraft operational problems. This paper describes two lunar shadow eclipse prediction models using a projection map approach and a line of intersection method by extending the Earth shadow eclipse models described by Srivastava et al. [10,11] for the Earth orbiting spacecraft. The attractive feature of both models is that they are much easier to implement. Both mathematical models have been simulated for two Indian low Earth orbiting spacecrafts: Oceansat-2, Saral-1, and two geostationary spacecrafts: GSAT-10, INSAT-4CR. Results obtained by the models compare well with lunar shadow model given by Escobal and Robertson [12], and high fidelity commercial software package, Systems Tool Kit (STK) of AGI.

  20. Infrared near-Earth-object survey modeling for observatories interior to the Earth's orbit

    Science.gov (United States)

    Buie, M.

    2014-07-01

    The search for and dynamical characterization of the near-Earth population of objects (NEOs) has been a busy topic for surveys for many years. Most of the work thus far has been from ground-based optical surveys such as the Catalina Sky Survey and LINEAR. These surveys have essentially reached a complete inventory of objects down to 1 km diameter and have shown that the known objects do not pose any significant impact threat. Smaller objects are correspondingly smaller threats but there are more of them and fewer of them have so far been discovered. The next generation of surveys is looking to extend their reach down to much smaller sizes. From an impact risk perspective, those objects as small as 30--40 m are still of interest (similar in size to the Tunguska bolide). Smaller objects than this are largely of interest from a space resource or in-situ analysis efforts. A recent mission concept promoted by the B612 Foundation and Ball Aerospace calls for an infrared survey telescope in a Venus-like orbit, known as the Sentinel Mission. This wide-field facility has been designed to complete the inventory down to a 140 m diameter while also providing substantial constraints on the NEO population down to a Tunguska-sized object. I have been working to develop a suite of tools to provide survey modeling for this class of survey telescope. The purpose of the tool is to uncover hidden complexities that govern mission design and operation while also working to quantitatively understand the orbit quality provided on its catalog of objects without additional followup assets. The baseline mission design calls for a 6.5 year survey lifetime. This survey model is a statistically based tool for establishing completeness as a function of object size and survey duration. Effects modeled include the ability to adjust the field-of-regard (includes all pointing restrictions), field-of-view, focal plane array fill factor, and the observatory orbit. Consequences tracked include time

  1. METRIC: A Dedicated Earth-Orbiting Spacecraft for Investigating Gravitational Physics and the Space Environment

    Science.gov (United States)

    Peron, R.; Lorenzini, E. C.

    2017-07-01

    A dedicated mission in low Earth orbit is proposed to test predictions of gravitational interaction theories and to directly measure the atmospheric density in a relevant altitude range, as well as to provide a metrological platform able to tie different space geodesy techniques. The concept foresees a small spacecraft to be placed in a dawn-dusk eccentric orbit between 450 and 1200 km of altitude. The spacecraft will be tracked from the ground with high precision, and a three-axis accelerometer package on-board will measure the non-gravitational accelerations acting on its surface. Estimates of parameters related to fundamental physics and geophysics should be obtained by a precise orbit determination, while the accelerometer data will be instrumental in constraining the atmospheric density. Along with the mission scientific objectives, a conceptual configuration is described together with an analysis of the dynamical environment experienced by the spacecraft and the acc! elerometer.

  2. Probable Rotation States of Rocket Bodies in Low Earth Orbit

    Science.gov (United States)

    Ojakangas, Gregory W.; Anz-Meador, P.; Cowardin, H.

    2012-01-01

    In order for Active Debris Removal to be accomplished, it is critically important to understand the probable rotation states of orbiting, spent rocket bodies. As compared to the question of characterizing small unresolved debris, in this problem there are several advantages: (1) objects are of known size, mass, shape and color, (2) they have typically been in orbit for a known period of time, (3) they are large enough that resolved images may be obtainable for verification of predicted orientation, and (4) the dynamical problem is simplified to first order by largely cylindrical symmetry. It is also nearly certain for realistic rocket bodies that internal friction is appreciable in the case where residual liquid or, to a lesser degree, unconsolidated solid fuels exist. Equations of motion have been developed for this problem in which internal friction as well as torques due to solar radiation, magnetic induction, and gravitational gradient are included. In the case of pure cylindrical symmetry, the results are compared to analytical predictions patterned after the standard approach for analysis of symmetrical tops. This is possible because solar radiation and gravitational torques may be treated as conservative. Agreement between results of both methods ensures their mutual validity. For monotone symmetric cylinders, solar radiation torque vanishes if the center of mass resides at the geometric center of the object. Results indicate that in the absence of solar radiation effects, rotation states tend toward an equilibrium configuration in which rotation is about the axis of maximum inertia, with the axis of minimum inertia directed toward the center of the earth. Solar radiation torque introduces a modification to this orientation. The equilibrium state is asymptotically approached within a characteristic timescale given by a simple ratio of relevant characterizing parameters for the body in question. Light curves are simulated for the expected asymptotic final

  3. An Assessment of Relativistic Effects for Low Earth Orbiters: The GRACE Satellites

    Science.gov (United States)

    2007-01-01

    IOP PUBLISHING METROLOGIA Metrologia 44 (2007) 484–490 doi:10.1088/0026-1394/44/6/007 An assessment of relativistic effects for low Earth orbiters...for the larger-eccentricity orbit is shown in figure 2(b). Metrologia , 44 (2007) 484–490 485 K M Larson et al Figure 1. Amplitude of the once/rev...486 Metrologia , 44 (2007) 484–490 Assessment of relativistic effects for low Earth orbiters combination was launched on TOPEX in 1992. Unfortunately

  4. Orbit Determination Error Analysis Results for the Triana Sun-Earth L2 Libration Point Mission

    Science.gov (United States)

    Marr, G.

    2003-01-01

    Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination error analysis results are presented for all phases of the Triana Sun-Earth L1 libration point mission and for the science data collection phase of a future Sun-Earth L2 libration point mission. The Triana spacecraft was nominally to be released by the Space Shuttle in a low Earth orbit, and this analysis focuses on that scenario. From the release orbit a transfer trajectory insertion (TTI) maneuver performed using a solid stage would increase the velocity be approximately 3.1 km/sec sending Triana on a direct trajectory to its mission orbit. The Triana mission orbit is a Sun-Earth L1 Lissajous orbit with a Sun-Earth-vehicle (SEV) angle between 4.0 and 15.0 degrees, which would be achieved after a Lissajous orbit insertion (LOI) maneuver at approximately launch plus 6 months. Because Triana was to be launched by the Space Shuttle, TTI could potentially occur over a 16 orbit range from low Earth orbit. This analysis was performed assuming TTI was performed from a low Earth orbit with an inclination of 28.5 degrees and assuming support from a combination of three Deep Space Network (DSN) stations, Goldstone, Canberra, and Madrid and four commercial Universal Space Network (USN) stations, Alaska, Hawaii, Perth, and Santiago. These ground stations would provide coherent two-way range and range rate tracking data usable for orbit determination. Larger range and range rate errors were assumed for the USN stations. Nominally, DSN support would end at TTI+144 hours assuming there were no USN problems. Post-TTI coverage for a range of TTI longitudes for a given nominal trajectory case were analyzed. The orbit determination error analysis after the first correction maneuver would be generally applicable to any libration point mission utilizing a direct trajectory.

  5. Impacts of Earth rotation parameters on GNSS ultra-rapid orbit prediction: Derivation and real-time correction

    Science.gov (United States)

    Wang, Qianxin; Hu, Chao; Xu, Tianhe; Chang, Guobin; Hernández Moraleda, Alberto

    2017-12-01

    Analysis centers (ACs) for global navigation satellite systems (GNSSs) cannot accurately obtain real-time Earth rotation parameters (ERPs). Thus, the prediction of ultra-rapid orbits in the international terrestrial reference system (ITRS) has to utilize the predicted ERPs issued by the International Earth Rotation and Reference Systems Service (IERS) or the International GNSS Service (IGS). In this study, the accuracy of ERPs predicted by IERS and IGS is analyzed. The error of the ERPs predicted for one day can reach 0.15 mas and 0.053 ms in polar motion and UT1-UTC direction, respectively. Then, the impact of ERP errors on ultra-rapid orbit prediction by GNSS is studied. The methods for orbit integration and frame transformation in orbit prediction with introduced ERP errors dominate the accuracy of the predicted orbit. Experimental results show that the transformation from the geocentric celestial references system (GCRS) to ITRS exerts the strongest effect on the accuracy of the predicted ultra-rapid orbit. To obtain the most accurate predicted ultra-rapid orbit, a corresponding real-time orbit correction method is developed. First, orbits without ERP-related errors are predicted on the basis of ITRS observed part of ultra-rapid orbit for use as reference. Then, the corresponding predicted orbit is transformed from GCRS to ITRS to adjust for the predicted ERPs. Finally, the corrected ERPs with error slopes are re-introduced to correct the predicted orbit in ITRS. To validate the proposed method, three experimental schemes are designed: function extrapolation, simulation experiments, and experiments with predicted ultra-rapid orbits and international GNSS Monitoring and Assessment System (iGMAS) products. Experimental results show that using the proposed correction method with IERS products considerably improved the accuracy of ultra-rapid orbit prediction (except the geosynchronous BeiDou orbits). The accuracy of orbit prediction is enhanced by at least 50

  6. The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets.

    Science.gov (United States)

    Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M

    2009-04-01

    We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary.

  7. Software and hardware implements for tracking low earth orbit (LEO) satellites

    OpenAIRE

    Rahal, Wassila Leila; Banabadji, Noureddine; Belbachir, Ahmed Hafid

    2008-01-01

    International audience; In this paper, we present a novel, precise and efficient tracking system for Low Earth Orbit (LEO) Satellites. We have developed a software (LAAR-Track) and a hardware interface for orbit determination based on using orbital elements, which are given by the NORAD (North American Aerospace Defence). Orbital perturbations, such as the atmospheric drag, the influence of the moon and the sun and the geopotential field have been considered for satellites trajectory determin...

  8. Effects of Low Earth Orbit on Docking Seal Materials

    Science.gov (United States)

    Imka, Emily C.; Asmar, Olivia C.; deGroh, Henry C., III; Banks, Bruce A.

    2014-01-01

    Spacecraft docking seals are typically made of silicone elastomers. When such seals are exposed to low Earth orbit (LEO) conditions, they can suffer damage from ultraviolet (UV) radiation and atomic oxygen (AO, or monoatomic oxygen, the predominant oxygen species in LEO). An experiment flew on the International Space Station (ISS) to measure the effects of LEO on seal materials S0383-70 and ELA-SA-401 and various mating counterface materials which included anodized aluminum. Samples flown in different orientations received different amounts of UV and AO. The hypotheses were that most of the damage would be from UV, and 10 days or more of exposure in LEO would badly damage the seals. Eighteen seals were exposed for 543 days in ram (windward), zenith (away from Earth), or wake (leeward) orientations, and 15 control samples (not flown) provided undamaged baseline leakage. To determine post-flight leak rates, each of the 33 seals were placed in an O-ring groove of a leak test fixture and pressure tested over time. Resistance temperature detectors (RTDs), pressure transducers, and LabVIEW (National Instruments) programs were used to measure and analyze the temperature and pressure and calculate leakage. Average leakage of control samples was 2.6 x 10(exp -7) lbs/day. LEO exposure did not considerably damage ELA-SA-401. The S0383-70 flight samples leaked at least 10 times more than ELA-SA-401 in all cases except one, demonstrating that ELA-SA-401 may be a more suitable sealing material in LEO. AO caused greater damage than UV; samples in ram orientation (receiving an AO fluence of 4.3 x 10(exp 21) atoms/(sq cm) and in wake (2.9x 10(exp 20) atoms/(sq cm)) leaked more than those in zenith orientation (1.58 x 10(exp 20) atoms/(sq cm)), whereas variations in UV exposure did not seem to affect the samples. Exposure to LEO did less damage to the seals than hypothesized, and the data did not support the conjecture that UV causes more damage than AO.

  9. Compendium of Single Event Effects Test Results for Commercial Off-The-Shelf and Standard Electronics for Low Earth Orbit and Deep Space Applications

    Science.gov (United States)

    Reddell, Brandon D.; Bailey, Charles R.; Nguyen, Kyson V.; O'Neill, Patrick M.; Wheeler, Scott; Gaza, Razvan; Cooper, Jaime; Kalb, Theodore; Patel, Chirag; Beach, Elden R.; hide

    2017-01-01

    We present the results of Single Event Effects (SEE) testing with high energy protons and with low and high energy heavy ions for electrical components considered for Low Earth Orbit (LEO) and for deep space applications.

  10. Compendium of Single Event Effects (SEE) Test Results for COTS and Standard Electronics for Low Earth Orbit and Deep Space Applications

    Science.gov (United States)

    Reddell, Brandon; Bailey, Chuck; Nguyen, Kyson; O'Neill, Patrick; Gaza, Razvan; Patel, Chirag; Cooper, Jaime; Kalb, Theodore

    2017-01-01

    We present the results of SEE testing with high energy protons and with low and high energy heavy ions. This paper summarizes test results for components considered for Low Earth Orbit and Deep Space applications.

  11. Conceptual radiometer design studies for Earth observations from low Earth orbit

    Science.gov (United States)

    Harrington, Richard F.

    1994-01-01

    A conceptual radiometer design study was performed to determine the optimum design approach for spaceborne radiometers in low Earth orbit. Radiometric system configurations which included total power radiometers, unbalanced Dicke radiometers, and balanced Dicke, or as known as noise injection, radiometers were studied. Radiometer receiver configurations which were analyzed included the direct detection radiometer receiver, the double sideband homodyne radiometer receiver, and the single sideband heterodyne radiometer receiver. Radiometer system performance was also studied. This included radiometric sensitivity analysis of the three different radiometer system configurations studied. Both external and internal calibration techniques were analyzed. An accuracy analysis with and without mismatch losses was performed. It was determined that the balanced Dicke radiometer system configuration with direct detection receivers and external calibrations was optimum where frequent calibration such as once per minute were not feasible.

  12. Extension of Earth-Moon libration point orbits with solar sail propulsion

    Science.gov (United States)

    Heiligers, Jeannette; Macdonald, Malcolm; Parker, Jeffrey S.

    2016-07-01

    This paper presents families of libration point orbits in the Earth-Moon system that originate from complementing the classical circular restricted three-body problem with a solar sail. Through the use of a differential correction scheme in combination with a continuation on the solar sail induced acceleration, families of Lyapunov, halo, vertical Lyapunov, Earth-centred, and distant retrograde orbits are created. As the solar sail circular restricted three-body problem is non-autonomous, a constraint defined within the differential correction scheme ensures that all orbits are periodic with the Sun's motion around the Earth-Moon system. The continuation method then starts from a classical libration point orbit with a suitable period and increases the solar sail acceleration magnitude to obtain families of orbits that are parametrised by this acceleration. Furthermore, different solar sail steering laws are considered (both in-plane and out-of-plane, and either fixed in the synodic frame or fixed with respect to the direction of Sunlight), adding to the wealth of families of solar sail enabled libration point orbits presented. Finally, the linear stability properties of the generated orbits are investigated to assess the need for active orbital control. It is shown that the solar sail induced acceleration can have a positive effect on the stability of some orbit families, especially those at the L2 point, but that it most often (further) destabilises the orbit. Active control will therefore be needed to ensure long-term survivability of these orbits.

  13. AMS_02 Particle Physics Detector Technologies Orbiting the Earth (1/2)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    AMS-02 has taken the high performance technologies used in particle physics and implemented them for use in low Earth orbit. Safety aspects for the Space Shuttle flight, that carried AMS_02 to the International Space Station, Space environment and inaccessibility during the life of AMS_02 are some of the aspects which have driven the design of the experiment. The technical challenges to build such a detector have been surmounted through the close collaboration amongst the AMS scientists and industries around the world. Their efforts have resulted in the development of new technologies and higher standards of precision.

  14. AMS_02 Particle Physics Detector Technologies Orbiting the Earth (2/2)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    AMS-02 has taken the high performance technologies used in particle physics and implemented them for use in low Earth orbit. Safety aspects for the Space Shuttle flight, that carried AMS_02 to the International Space Station, Space environment and inaccessibility during the life of AMS_02 are some of the aspects which have driven the design of the experiment. The technical challenges to build such a detector have been surmounted through the close collaboration amongst the AMS scientists and industries around the world. Their efforts have resulted in the development of new technologies and higher standards of precision.

  15. Rings of earth. [orbiting bands of space debris

    Science.gov (United States)

    Goldstein, Richard M.; Randolph, L. W.

    1992-01-01

    Small particles moving at an orbital velocity of 7.6 kilometers per second can present a considerable hazard to human activity in space. For astronauts outside of the protective shielding of their space vehicles, such particles can be lethal. The powerful radar at NASA's Goldstone Deep Communications Complex was used to monitor such orbital debris. This radar can detect metallic objects as small as 1.8 mm in diameter at 600 km altitude. The results of the preliminary survey show a flux (at 600 km altitude) of 6.4 objects per square kilometer per day of equivalent size of 1.8 mm or larger. Forty percent of the observed particles appear to be concentrated into two orbits. An orbital ring with the same inclination as the radar (35.1 degrees) is suggested. However, an orbital band with a much higher inclination (66 degrees) is also a possibility.

  16. Collisional cascading - The limits of population growth in low earth orbit

    Science.gov (United States)

    Kessler, Donald J.

    1991-01-01

    Random collisions between made-made objects in earth orbit will lead to a significant source of orbital debris, but there are a number of uncertainties in these models, and additional analysis and data are required to fully characterize the future environment. However, the nature of these uncertainties are such that while the future environment is uncertain, the fact that collisions will control the future environment is less uncertain. The data that already exist is sufficient to show that cascading collisions will control the future debris environment with no, or very minor increases in the current low-earth-orbit population. Two populations control this process: explosion fragments and expended rocket bodies and payloads. Practices are already changing to limit explosions in low earth orbit; it is necessary to begin limiting the number of expended rocket bodies and payloads in orbit.

  17. TWINKLE - A Low Earth Orbit Visible and Infrared Exoplanet Spectroscopy Observatory

    Science.gov (United States)

    Tessenyi, M.; Savini, G.; Tinetti, G.; Tennyson, J.; Dhesi, M.; Joshua, M.

    2017-07-01

    Twinkle is a space mission designed for visible and near-IR spectroscopic observations of extrasolar planets. Twinkle's highly stable instrument will allow the photometric and spectroscopic observation of a wide range of planetary classes around different types of stars, with a focus on bright sources close to the ecliptic. The planets will be observed through transit and eclipse photometry and spectroscopy, as well as phase curves, eclipse mapping and multiple narrow-band time-series. The targets observed by Twinkle will be composed of known exoplanets mainly discovered by existing and upcoming ground surveys in our galaxy and will also feature new discoveries by space observatories (K2, GAIA, Cheops, TESS). Twinkle is a small satellite with a payload designed to perform high-quality astrophysical observations while adapting to the design of an existing Low Earth Orbit commercial satellite platform. The SSTL-300 bus, to be launched into a low-Earth sun-synchronous polar orbit by 2019, will carry a half-meter class telescope with two instruments (visible and near-IR spectrographs - between 0.4 and 4.5μm - with resolving power R˜300 at the lower end of the wavelength scale) using mostly flight proven spacecraft systems designed by Surrey Satellite Technology Ltd and a combination of high TRL instrumentation and a few lower TRL elements built by a consortium of UK institutes. The Twinkle design will enable the observation of the chemical composition and weather of at least 100 exoplanets in the Milky Way, including super-Earths (rocky planets 1-10 times the mass of Earth), Neptunes, sub-Neptunes and gas giants like Jupiter. It will also allow the follow-up photometric observations of 1000+ exoplanets in the visible and infrared, as well as observations of Solar system objects, bright stars and disks.

  18. Evaluation of Aerodynamic Drag and Torque for External Tanks in Low Earth Orbit

    National Research Council Canada - National Science Library

    Stone, William C; Witzgall, Christoph

    2006-01-01

    A numerical procedure is described in which the aerodynamic drag and torque in low Earth orbit are calculated for a prototype Space Shuttle external tank and its components, the "LO2" and "LH2" tanks...

  19. Comprehensive NASA Cis-Lunar Earth Moon Libration Orbit Reference and Web Application Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To finalize a comprehensive NASA Cis-Lunar / Earth-Moon Libration Orbit Reference and Web Application begun using FY13 IRAD funding approved in May 2013. This GSFC...

  20. Single Event Effects Testing For Low Earth Orbit Missions with Neutrons

    Science.gov (United States)

    Reddell, Brandon; O'Neill, Pat; Bailey, Chuck; Nguyen, Kyson

    2015-01-01

    Neutrons can effectively be used to screen electronic parts intended to be used in Low Earth Orbit. This paper compares neutron with proton environments in spacecraft and discusses recent comparison testing.

  1. The Coverage Analysis for Low Earth Orbiting Satellites at Low Elevation

    OpenAIRE

    Shkelzen Cakaj; Bexhet Kamo; Algenti Lala; Alban Rakipi

    2014-01-01

    Low Earth Orbit (LEO) satellites are used for public networking and for scientific purposes. Communication via satellite begins when the satellite is positioned in its orbital position. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region. The duration of the visibility and the communication vary for each LEO satellite pass over the station, since LEO satellites move too fast over the Earth. The satellite coverage area is defined as a regio...

  2. Earth Observatory Satellite system definition study. Report 1: Orbit/launch vehicle trade-off studies and recommendations

    Science.gov (United States)

    1974-01-01

    A summary of the constraints and requirements on the Earth Observatory Satellite (EOS-A) orbit and launch vehicle analysis is presented. The propulsion system (hydrazine) and the launch vehicle (Delta 2910) selected for EOS-A are examined. The rationale for the selection of the recommended orbital altitude of 418 nautical miles is explained. The original analysis was based on the EOS-A mission with the Thematic Mapper and the High Resolution Pointable Imager. The impact of the revised mission model is analyzed to show how the new mission model affects the previously defined propulsion system, launch vehicle, and orbit. A table is provided to show all aspects of the EOS multiple mission concepts. The subjects considered include the following: (1) mission orbit analysis, (2) spacecraft parametric performance analysis, (3) launch system performance analysis, and (4) orbits/launch vehicle selection.

  3. A model perspective on orbital forcing of monsoons and Mediterranean climate using EC-Earth

    NARCIS (Netherlands)

    Bosmans, J.H.C.|info:eu-repo/dai/nl/344765490

    2014-01-01

    This thesis focuses on orbitally forced changes of monsoons and Mediterranean climate. Changes in the shape of the Earths orbit around the Sun and its rotational axis govern the seasonal and latitudinal distribution of incoming solar radiation on time scales of thousands to millions of years. The

  4. A KAM Tori Algorithm for Earth Satellite Orbits

    Science.gov (United States)

    Wiesel, William E.

    2017-12-01

    This paper offers a new approach for constructing Kolmogorov - Arnold - Moser (KAM) tori for orbits in the full potential for a non-spherical planet. The Hamilton - Jacobi equation is solved numerically by a Newton-Rhapson iteration, achieving convergence to machine precision, and still retaining literal variable dependence. Similar iteration methods allow correcting the orbital frequencies, and permit the calculation of the state transition matrix for the full problem. Some initial numerical examples are offered.

  5. Laser propulsion to earth orbit. Has its time come?

    Science.gov (United States)

    Kantrowitz, Arthur

    1989-01-01

    Recent developments in high energy lasers, adaptive optics, and atmospheric transmission bring laser propulsion much closer to realization. Proposed here is a reference vehicle for study which consists of payload and solid propellant (e.g. ice). A suitable laser pulse is proposed for using a Laser Supported Detonation wave to produce thrust efficiently. It seems likely that a minimum system (10 Mw CO2 laser and 10 m dia. mirror) could be constructed for about $150 M. This minimum system could launch payloads of about 13 kg to a 400 km orbit every 10 minutes. The annual launch capability would be about 683 tons times the duty factor. Laser propulsion would be an order of magnitude cheaper than chemical rockets if the duty factor was 20 percent (10,000 launches/yr). Launches beyond that would be even cheaper. The chief problem which needs to be addressed before these possibilities could be realized is the design of a propellant to turn laser energy into thrust efficiently and to withstand the launch environment.

  6. On the possible values of the orbit distance between a near-Earth asteroid and the Earth

    Science.gov (United States)

    Gronchi, G. F.; Valsecchi, G. B.

    2013-03-01

    We consider all the possible trajectories of a near-Earth asteroid (NEA), corresponding to the whole set of heliocentric orbital elements with perihelion distance q ≤ 1.3 au and eccentricity e ≤ 1 (NEA class). For these hypothetical trajectories, we study the range of the values of the distance from the trajectory of the Earth (assumed on a circular orbit) as a function of selected orbital elements of the asteroid. The results of this geometric approach are useful to explain some aspects of the orbital distribution of the known NEAs. We also show that the maximal orbit distance between an object in the NEA class and the Earth is attained by a parabolic orbit, with apsidal line orthogonal to the ecliptic plane. It turns out that the threshold value of q for the NEA class (qmax = 1.3 au) is very close to a critical value, below which the above result is not valid. `Nothing was visible, nor could be visible, to us, except Straight Lines', E. A. Abbott, Flatland.

  7. Confirming the transit of the Earth-mass planet orbiting Alpha Centauri B

    Science.gov (United States)

    Demory, Brice-Olivier

    2013-10-01

    One of the most fascinating exoplanet findings of the past years is undoubtedly the discovery of an Earth-mass exoplanet orbiting Alpha Centauri B. Alpha Cen Bb orbits one component of the closest stellar system to the Earth and has the potential to become a true Rosetta stone in exoplanet science, if its transiting nature were revealed. In 2013, we observed Alpha Centauri B during 16 orbits with HST/STIS to search for the transit of Alpha Cen Bb. We recently carried out in-depth photometric analyses of this dataset that resulted in the clear detection of a transit-shaped pattern. Several factors, however, prevent us from securing the planetary nature of the signal found in the STIS time-series. Now that we know where and when to look for, we propose to confirm the repeatability of this signal and to firmly establish Alpha Cen Bb's existence and tighten its physical and orbital properties. We base our observing strategy on the successful approach employed just one year ago with the same instrument. Until Aug 9th 2014, combination of HST available roll angles, Alpha Cen binary separation and position angle will match the nearly-ideal configuration we had in July 2013. It would even be possible to benefit from CVZ status from 24/7/2014 to 28/7/2014, in which one transit of Alpha Centauri Bb is expected. HST/STIS is the only facility able to confirm a transit from such a small planet at a high confidence level.

  8. A Framework for Orbital Performance Evaluation in Distributed Space Missions for Earth Observation

    Science.gov (United States)

    Nag, Sreeja; LeMoigne-Stewart, Jacqueline; Miller, David W.; de Weck, Olivier

    2015-01-01

    Distributed Space Missions (DSMs) are gaining momentum in their application to earth science missions owing to their unique ability to increase observation sampling in spatial, spectral and temporal dimensions simultaneously. DSM architectures have a large number of design variables and since they are expected to increase mission flexibility, scalability, evolvability and robustness, their design is a complex problem with many variables and objectives affecting performance. There are very few open-access tools available to explore the tradespace of variables which allow performance assessment and are easy to plug into science goals, and therefore select the most optimal design. This paper presents a software tool developed on the MATLAB engine interfacing with STK, for DSM orbit design and selection. It is capable of generating thousands of homogeneous constellation or formation flight architectures based on pre-defined design variable ranges and sizing those architectures in terms of predefined performance metrics. The metrics can be input into observing system simulation experiments, as available from the science teams, allowing dynamic coupling of science and engineering designs. Design variables include but are not restricted to constellation type, formation flight type, FOV of instrument, altitude and inclination of chief orbits, differential orbital elements, leader satellites, latitudes or regions of interest, planes and satellite numbers. Intermediate performance metrics include angular coverage, number of accesses, revisit coverage, access deterioration over time at every point of the Earth's grid. The orbit design process can be streamlined and variables more bounded along the way, owing to the availability of low fidelity and low complexity models such as corrected HCW equations up to high precision STK models with J2 and drag. The tool can thus help any scientist or program manager select pre-Phase A, Pareto optimal DSM designs for a variety of science

  9. Large-size space debris flyby in low earth orbits

    Science.gov (United States)

    Baranov, A. A.; Grishko, D. A.; Razoumny, Y. N.

    2017-09-01

    the analysis of NORAD catalogue of space objects executed with respect to the overall sizes of upper-stages and last stages of carrier rockets allows the classification of 5 groups of large-size space debris (LSSD). These groups are defined according to the proximity of orbital inclinations of the involved objects. The orbits within a group have various values of deviations in the Right Ascension of the Ascending Node (RAAN). It is proposed to use the RAANs deviations' evolution portrait to clarify the orbital planes' relative spatial distribution in a group so that the RAAN deviations should be calculated with respect to the concrete precessing orbital plane of the concrete object. In case of the first three groups (inclinations i = 71°, i = 74°, i = 81°) the straight lines of the RAAN relative deviations almost do not intersect each other. So the simple, successive flyby of group's elements is effective, but the significant value of total Δ V is required to form drift orbits. In case of the fifth group (Sun-synchronous orbits) these straight lines chaotically intersect each other for many times due to the noticeable differences in values of semi-major axes and orbital inclinations. The intersections' existence makes it possible to create such a flyby sequence for LSSD group when the orbit of one LSSD object simultaneously serves as the drift orbit to attain another LSSD object. This flyby scheme requiring less Δ V was called "diagonal." The RAANs deviations' evolution portrait built for the fourth group (to be studied in the paper) contains both types of lines, so the simultaneous combination of diagonal and successive flyby schemes is possible. The value of total Δ V and temporal costs were calculated to cover all the elements of the 4th group. The article is also enriched by the results obtained for the flyby problem solution in case of all the five mentioned LSSD groups. The general recommendations are given concerned with the required reserve of total

  10. Measuring the Eccentricity of the Earth's Orbit with a Nail and a Piece of Plywood

    Science.gov (United States)

    Lahaye, Thierry

    2012-01-01

    I describe how to obtain a rather good experimental determination of the eccentricity of the Earth's orbit, as well as the obliquity of the Earth's rotation axis, by measuring, over the course of a year, the elevation of the Sun as a function of time during a day. With a very simple "instrument" consisting of an elementary sundial, first-year…

  11. The Orbit of Planet Earth in the Last 150 Million Years

    NARCIS (Netherlands)

    Noort, van den P.C.

    2011-01-01

    The structure of the world is a construction of philosophers and scientists. It changed all the time. Nowadays we have a chaotic Solar System. The orbit of Earth changes, therefore, on the very long run. With it changed the UV- radiation on the surface of Earth, influencing the number of mutations.

  12. Novel Solar Sail Mission Concepts for High-Latitude Earth and Lunar Observation

    NARCIS (Netherlands)

    Heiligers, M.J.; Parker, Jeffrey S.; Macdonald, Malcolm

    2016-01-01

    This paper proposes the use of solar sail periodic orbits in the Earth-Moon system for ob-servation of the high-latitudes of the Earth and Moon. At the Earth, the high-latitudes will be crucial in answering questions concerning global climate change, monitoring space weather events and ensuring

  13. Guidance Scheme for Modulation of Drag Devices to Enable Return from Low Earth Orbit

    Science.gov (United States)

    Dutta, Soumyo; Bowes, Angela L.; Cianciolo, Alicia D.; Glass, Christopher E.; Powell, Richard W.

    2017-01-01

    Passive drag devices provide opportunities to return payloads from low Earth orbits quickly without using onboard propulsive systems to de-orbit the spacecraft. However, one potential disadvantage of such systems has been the lack of landing accuracy. Drag modulation or changing the shape of the drag device during flight offer a way to control the de-orbit trajectory and target a specific landing location. This paper discusses a candidate passive drag based system, called Exo-brake, as well as efforts to model the dynamics of the vehicle as it de-orbits and guidance schemes used to control the trajectory. Such systems can enable quick return of payloads from low Earth orbit assets like the International Space Station without the use of large re-entry cargo capsules or propulsive systems.

  14. Biofilms On Orbit and On Earth: Current Methods, Future Needs

    Science.gov (United States)

    Vega, Leticia

    2013-01-01

    Biofilms have played a significant role on the effectiveness of life support hardware on the Space Shuttle and International Space Station (ISS). This presentation will discuss how biofilms impact flight hardware, how on orbit biofilms are analyzed from an engineering and research perspective, and future needs to analyze and utilize biofilms for long duration, deep space missions.

  15. Comprehensive evaluation of attitude and orbit estimation using real earth magnetic field data

    Science.gov (United States)

    Deutschmann, Julie; Bar-Itzhack, Itzhack

    1997-01-01

    A single, augmented extended Kalman filter (EKF) which simultaneously and autonomously estimates spacecraft attitude and orbit was developed and tested with simulated and real magnetometer and rate data. Since the earth's magnetic field is a function of time and position, and since time is accurately known, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft's orbit, are a function of orbit and attitude errors. These differences can be used to estimate the orbit and attitude. The test results of the EKF with magnetometer and gyro data from three NASA satellites are presented and evaluated.

  16. UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Rugheimer, S.; Sasselov, D. [Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge (United States); Segura, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México (Mexico); Kaltenegger, L., E-mail: srugheimer@cfa.harvard.edu [Carl Sagan Institute, Cornell University, Ithaca, NY 14853 (United States)

    2015-06-10

    The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

  17. Investigation of Teflon FEP Embrittlement on Spacecraft in Low-Earth Orbit

    Science.gov (United States)

    deGroh, Kim K.; Banks, Bruce A.

    1997-01-01

    Teflon fluorinated ethylene propylene (FEP) (DuPont) is commonly used on exterior spacecraft surfaces for thermal control in the low-Earth orbit environment. Silverized or aluminized Teflon FEP is used for the outer layers of the thermal control blanket because of its high reflectance, low solar absorptance, and high thermal emittance. Teflon FEP is also desirable because, compared with other spacecraft polymers (such as Kapton), it has relatively high resistance to atomic oxygen erosion. Because of its comparably low atomic oxygen erosion yield, Teflon FEP has been used unprotected in the space environment. Samples of Teflon FEP from the Long Duration Exposure Facility (LDEF) and the Hubble Space Telescope (retrieved during its first servicing mission) were evaluated for solar-induced embrittlement and for synergistic effects of solar degradation and atomic oxygen.

  18. Evolution of Satellite Imagers and Sounders for Low Earth Orbit and Technology Directions at NASA

    Science.gov (United States)

    Pagano, Thomas S.; McClain, Charles R.

    2010-01-01

    Imagers and Sounders for Low Earth Orbit (LEO) provide fundamental global daily observations of the Earth System for scientists, researchers, and operational weather agencies. The imager provides the nominal 1-2 km spatial resolution images with global coverage in multiple spectral bands for a wide range of uses including ocean color, vegetation indices, aerosol, snow and cloud properties, and sea surface temperature. The sounder provides vertical profiles of atmospheric temperature, water vapor cloud properties, and trace gases including ozone, carbon monoxide, methane and carbon dioxide. Performance capabilities of these systems has evolved with the optical and sensing technologies of the decade. Individual detectors were incorporated on some of the first imagers and sounders that evolved to linear array technology in the '80's. Signal-to-noise constraints limited these systems to either broad spectral resolution as in the case of the imager, or low spatial resolution as in the case of the sounder. Today's area 2-dimensional large format array technology enables high spatial and high spectral resolution to be incorporated into a single instrument. This places new constraints on the design of these systems and enables new capabilities for scientists to examine the complex processes governing the Earth System.

  19. A Wide Field Auroral Imager (WFAI for low Earth orbit missions

    Directory of Open Access Journals (Sweden)

    N. P. Bannister

    2007-03-01

    Full Text Available A comprehensive understanding of the solar wind interaction with Earth's coupled magnetosphere-ionosphere system requires an ability to observe the charged particle environment and auroral activity from the same platform, generating particle and photon image data which are matched in time and location. While unambiguous identification of the particles giving rise to the aurora requires a Low Earth Orbit satellite, obtaining adequate spatial coverage of aurorae with the relatively limited field of view of current space bourne auroral imaging systems requires much higher orbits. A goal for future satellite missions, therefore, is the development of compact, wide field-of-view optics permitting high spatial and temporal resolution ultraviolet imaging of the aurora from small spacecraft in low polar orbit. Microchannel plate optics offer a method of achieving the required performance. We describe a new, compact instrument design which can observe a wide field-of-view with the required spatial resolution. We report the focusing of 121.6 nm radiation using a spherically-slumped, square-pore microchannel plate with a focal length of 32 mm and an F number of 0.7. Measurements are compared with detailed ray-trace simulations of imaging performance. The angular resolution is 2.7±0.2° for the prototype, corresponding to a footprint ~33 km in diameter for an aurora altitude of 110 km and a spacecraft altitude of 800 km. In preliminary analysis, a more recent optic has demonstrated a full width at half maximum of 5.0±0.3 arcminutes, corresponding to a footprint of ~1 km from the same spacecraft altitude. We further report the imaging properties of a convex microchannel plate detector with planar resistive anode readout; this detector, whose active surface has a radius of curvature of only 100 mm, is shown to meet the spatial resolution and sensitivity requirements of the new wide field auroral imager (WFAI.

  20. Application of KAM Theorem to Earth Orbiting Satellites

    Science.gov (United States)

    2009-03-01

    kids , for constantly reminding me that there was more than just school to keep me busy. Bryan D. Little v Table of Contents Page Abstract...Gunter, Z. Kang, P. Nagel, R. Pastor , T. Pekker, S. Poole, and F. Wang. “GGM02 An im- proved Earth gravity field model from GRACE”. Journal of Geodesy

  1. Low-thrust transfers from distant retrograde orbits to L2 halo orbits in the earth-moon system

    NARCIS (Netherlands)

    Parrish, N.L.; Parker, Jeffrey S.; Hughes, S.P.; Heiligers, M.J.

    2016-01-01

    Enable future missions Any mission to a DRO or halo orbit could benefit from the capability to transfer between these orbits Chemical propulsion could be used for these transfers, but at high propellant cost Fill gaps in knowledge A variety of transfers using SEP or solar sails have been studied for

  2. Efficient methods for determining precise orbits of low Earth orbiters using the Global Positioning System

    Science.gov (United States)

    Bock, Heike

    The main part of this work dealt with the development and evaluation of efficient methods for precise orbit determination of LEOs. A kinematic approach using GPS zero-difference observations was developed (program LEOKIN) and a procedure for generation of dynamic and reduced-dynamic orbits was presented (program SATORB). The procedures have been tested using long GPS data series gathered by two LEO satellites, namely CHAMP and SAC-C. An external comparison was available for the time interval of the eleven days of the IGS CHAMP test campaign (May 20 to 30, 2001). The orbit solution generated at the Technical University of Munich (TUM), Germany, using the Bernese GPS Software was used for this purpose. The TUM-solution is believed to be one of the best solutions contributing to the IGS test campaign. Comparisons with this solution showed that both our best kinematic trajectory and a post-fit reduced-dynamic orbit based on this kinematic solution compare within an RMS error per coordinate (of a Helmert transformation) of about 10 cm with the TUM-solutions. This indicates that LEO orbits with a quality of about 10 cm result from our analyses. The goal of developing efficient methods for precise orbit determination of LEOs is therefore achieved with the zero-difference kinematic point positioning procedure in LEOKIN and the program SATORB to generate reduced-dynamic orbits. It is worth mentioning that the procedure, when using only code observations as input, results in reduced-dynamic orbits with a qualitiy of already 30 cm RMS.

  3. Investigating fundamental physics and space environment with a dedicated Earth-orbiting spacecraft

    Science.gov (United States)

    Peron, Roberto

    The near-Earth environment is a place of first choice for performing fundamental physics experiments, given its proximity to Earth and at the same time being relatively quiet dynamically for particular orbital arrangements. This environment also sees a rich phenomenology for what concerns gravitation. In fact, the general theory of relativity is an incredibly accurate description of gravitational phenomenology. However, its overall validity is being questioned by the theories that aim at reconciling it with the microscopic domain. Challenges come also from the ‘mysteries’ of Dark Matter and Dark Energy, though mainly at scales from the galactic up to the cosmological. It is therefore important to precisely test the consequences of the theory -- as well as those of competing ones -- at all the accessible scales. At the same time, the development of high-precision experimental space techniques, which are needed for tests in fundamental physics, opens the way to complementary applications. The growth of the (man-made) orbital debris population is creating problems to the future development of space. The year 2009 witnessed the first accidental collision between two satellites in orbit (Iridium and Cosmos) that led to the creation of more debris. International and national agencies are intervening by issuing and/or adopting guidelines to mitigate the growth of orbital debris. A central tenet of these guidelines requires a presence in space shorter than 25 years to satellites in low Earth orbit (LEO) after the conclusion of their operational lives. However, the determination of the natural lifetime of a satellite in LEO is very uncertain due to a large extent to the short-term and long-term variability of the atmospheric density in LEO and the comparatively low-accuracy of atmospheric density models. Many satellites orbiting in the 500-1200 km region with circular or elliptical orbits will be hard pressed to establish before flight whether or not they meet the 25

  4. Computer subroutines for estimation of human exposure to radiation in low Earth orbit

    Science.gov (United States)

    Cucinotta, F. A.; Wilson, J. W.

    1985-01-01

    Computer subroutines to calculate human exposure to trapped radiations in low Earth orbit (LEO) on the basis of a simple approximation of the human geometry by spherical shell shields of varying thickness are presented and detailed. The subroutines calculate the dose to critical body organs and the fraction of exposure limit reached as a function of altitude of orbit, degree of inclination, shield thickness, and days in mission. Exposure rates are compared with current exposure limits.

  5. A Low Cost Automatic Detection and Ranging System for Space Surveillance in the Medium Earth Orbit Region and Beyond

    Science.gov (United States)

    Danescu, Radu; Ciurte, Anca; Turcu, Vlad

    2014-01-01

    The space around the Earth is filled with man-made objects, which orbit the planet at altitudes ranging from hundreds to tens of thousands of kilometers. Keeping an eye on all objects in Earth's orbit, useful and not useful, operational or not, is known as Space Surveillance. Due to cost considerations, the space surveillance solutions beyond the Low Earth Orbit region are mainly based on optical instruments. This paper presents a solution for real-time automatic detection and ranging of space objects of altitudes ranging from below the Medium Earth Orbit up to 40,000 km, based on two low cost observation systems built using commercial cameras and marginally professional telescopes, placed 37 km apart, operating as a large baseline stereovision system. The telescopes are pointed towards any visible region of the sky, and the system is able to automatically calibrate the orientation parameters using automatic matching of reference stars from an online catalog, with a very high tolerance for the initial guess of the sky region and camera orientation. The difference between the left and right image of a synchronized stereo pair is used for automatic detection of the satellite pixels, using an original difference computation algorithm that is capable of high sensitivity and a low false positive rate. The use of stereovision provides a strong means of removing false positives, and avoids the need for prior knowledge of the orbits observed, the system being able to detect at the same time all types of objects that fall within the measurement range and are visible on the image. PMID:24521941

  6. Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Zellar, Ronald S.; Fong, Wai H; Krainak, Michael A.; Neumann, Gregory A.; Smith, David E.

    2013-01-01

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  7. Free space laser communication experiments from Earth to the Lunar Reconnaissance Orbiter in lunar orbit.

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R; Hoffman, Evan D; Mao, Dandan; McGarry, Jan F; McIntire, Leva; Zellar, Ronald S; Davidson, Frederic M; Fong, Wai H; Krainak, Michael A; Neumann, Gregory A; Zuber, Maria T; Smith, David E

    2013-01-28

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  8. ADCS controllers comparison for small satellitess in Low Earth Orbit

    Science.gov (United States)

    Calvo, Daniel; Laverón-Simavilla, Ana; Lapuerta, Victoria

    2016-07-01

    Fuzzy logic controllers are flexible and simple, suitable for small satellites Attitude Determination and Control Subsystems (ADCS). In a previous work, a tailored Fuzzy controller was designed for a nanosatellite. Its performance and efficiency were compared with a traditional Proportional Integrative Derivative (PID) controller within the same specific mission. The orbit height varied along the mission from injection at around 380 km down to 200 km height, and the mission required pointing accuracy over the whole time. Due to both, the requirements imposed by such a low orbit, and the limitations in the power available for the attitude control, an efficient ADCS is required. Both methodologies, fuzzy and PID, were fine-tuned using an automated procedure to grant maximum efficiency with fixed performances. The simulations showed that the Fuzzy controller is much more efficient (up to 65% less power required) in single manoeuvres, achieving similar, or even better, precision than the PID. The accuracy and efficiency improvement of the Fuzzy controller increase with orbit height because the environmental disturbances decrease, approaching the ideal scenario. However, the controllers are meant to be used in a vast range of situations and configurations which exceed those used in the calibration process carried out in the previous work. To assess the suitability and performance of both controllers in a wider framework, parametric and statistical methods have been applied using the Monte Carlo technique. Several parameters have been modified randomly at the beginning of each simulation: the moments of inertia of the whole satellite and of the momentum wheel, the residual magnetic dipole and the initial conditions of the test. These parameters have been chosen because they are the main source of uncertainty during the design phase. The variables used for the analysis are the error (critical for science) and the operation cost (which impacts the mission lifetime and

  9. Lissajous Orbit Control for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission

    Science.gov (United States)

    Roberts, Craig; Case, Sarah; Reagoso, John

    2015-01-01

    DSCOVR Lissajous Orbit sized such that orbit track never extends beyond 15 degrees from Earth-Sun line (as seen from Earth). Requiring delta-V maneuvers, control orbit to obey a Solar Exclusion Zone (SEZ) cone of half-angle 4 degrees about the Earth-Sun line. Spacecraft should never be less than 4 degrees from solar center as seen from Earth. Following Lissajous Orbit Insertion (LOI), DSCOVR should be in an opening phase that just skirts the 4-degree SEZ. Maximizes time to the point where a closing Lissajous will require avoidance maneuvers to keep it out of the SEZ. Station keeping maneuvers should take no more than 15 minutes.

  10. Evaluation of thermal control coatings for use on solar dynamic radiators in low earth orbit

    Science.gov (United States)

    Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.

    1991-01-01

    Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

  11. Temporal Evolution of the Plasma Sheath Surrounding Solar Cells in Low Earth Orbit

    Science.gov (United States)

    Willis, Emily M.; Pour, Maria Z. A.

    2017-01-01

    High voltage solar array interactions with the space environment can have a significant impact on array performance and spacecraft charging. Over the past 10 years, data from the International Space Station has allowed for detailed observations of these interactions over long periods of time. Some of the surprising observations have been floating potential transients, which were not expected and are not reproduced by existing models. In order to understand the underlying processes producing these transients, the temporal evolution of the plasma sheath surrounding the solar cells in low Earth orbit is being investigated. This study includes lumped element modeling and particle-in-cell simulation methods. This presentation will focus on recent results from the on-going investigations.

  12. Long-Duration Human Habitation Beyond Low-Earth Orbit: Why is the Near Future Critical?

    Science.gov (United States)

    Thronson, Harley A.; Lester, Daniel; Hatfield, C. A.

    2011-01-01

    For more than a decade, habitation systems capable of comfortable human occupation and effective operations beyond low-Earth orbit (LEO) for more than a few weeks have been a priority recommendation to NASA. This capability is a lynch pin for human exploration beyond the Earth-Moon system. Here we describe briefly some relevant concepts and discuss justifications in the current political and financial environment for why near-term human habitation systems beyond LEO is an imperative.

  13. Early Mission Orbit Determination Error Analysis Results for Low-Earth Orbiting Missions using TDRSS Differenced One-way Doppler Tracking Data

    Science.gov (United States)

    Marr, Greg C.

    2003-01-01

    Differencing multiple, simultaneous Tracking and Data Relay Satellite System (TDRSS) one-way Doppler passes can yield metric tracking data usable for orbit determination for (low-cost) spacecraft which do not have TDRSS transponders or local oscillators stable enough to allow the one-way TDRSS Doppler tracking data to be used for early mission orbit determination. Orbit determination error analysis results are provided for low Earth orbiting spacecraft for various early mission tracking scenarios.

  14. Comprehensive Evaluation of Attitude and Orbit Estimation Using Actual Earth Magnetic Field Data

    Science.gov (United States)

    Deutschmann, Julie K.; Bar-Itzhack, Itzhack Y.

    2000-01-01

    A single, augmented Extended Kalman Filter (EKF), which simultaneously and autonomously estimates spacecraft attitude and orbit has been developed and successfully tested with real magnetometer and gyro data only. Because the earth magnetic field is a function of time and position, and because time is known quite precisely, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both orbit and attitude errors. Thus, conceivably these differences could be used to estimate both orbit and attitude; an observability study validated this assumption. The results of testing the EKF with actual magnetometer and gyro data, from four satellites supported by the NASA Goddard Space Flight Center (GSFC) Guidance, Navigation, and Control Center, are presented and evaluated. They confirm the assumption that a single EKF can estimate both attitude and orbit when using gyros and magnetometers only.

  15. Prevalence of Earth-size planets orbiting Sun-like stars

    Science.gov (United States)

    Petigura, Erik A.; Howard, Andrew W.; Marcy, Geoffrey W.

    2013-01-01

    Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration’s Kepler mission. We found 603 planets, including 10 that are Earth size () and receive comparable levels of stellar energy to that of Earth (). We account for Kepler’s imperfect detectability of such planets by injecting synthetic planet–caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ∼200 d. Extrapolating, one finds % of Sun-like stars harbor an Earth-size planet with orbital periods of 200–400 d. PMID:24191033

  16. Prevalence of Earth-size planets orbiting Sun-like stars.

    Science.gov (United States)

    Petigura, Erik A; Howard, Andrew W; Marcy, Geoffrey W

    2013-11-26

    Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration's Kepler mission. We found 603 planets, including 10 that are Earth size ( ) and receive comparable levels of stellar energy to that of Earth (1 - 2 R[Symbol: see text] ). We account for Kepler's imperfect detectability of such planets by injecting synthetic planet-caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ~200 d. Extrapolating, one finds 5.7(-2.2)(+1.7)% of Sun-like stars harbor an Earth-size planet with orbital periods of 200-400 d.

  17. Probable Rotation States of Rocket Bodies in Low Earth Orbit

    Science.gov (United States)

    Ojakangas, G.; Anz-Meador, P.; Cowardin, H.

    2012-09-01

    In order for Active Debris Removal to be accomplished, it is critically important to understand the probable rotation states of orbiting, spent rocket bodies (RBs). However, rotational dynamics is non-intuitive and misconceptions are common. Determinations of rotation and precession rates from light curves have been published that are inconsistent with the theory presented here. In a state of free precession, the total angular momentum of the object is constant, while kinetic energy decreases due to internal friction, approaching rotation about the axis of maximum inertia. For solid internal friction the timescale is hundreds to thousands of years for quality factors of ~100 and assuming metallic rigidities, but for friction in partially-filled liquid fuel tanks we predict that the preferred rotational state is approached rapidly, within days to months. However, history has shown that theoretical predictions of the timescale have been notoriously inaccurate. In free precession, the 3-1-3 Euler angle rates dphi/dt (precession rate of long axis about fixed angular momentum with cone angle theta) and dpsi/dt (roll rate around long axis) have comparable magnitudes until very close to theta=pi/2, so that otherwise the true rotation period is not simply twice the primary light curve period. Furthermore dtheta/dt, nonzero due to friction, becomes asymptotically smaller as theta=pi/2 is approached, so that theta can linger within several degrees of flat spin for a relatively long time. Such a condition is likely common, and cannot be distinguished from the wobble of a cylinder with a skewed inertia tensor unless the RB has non-axisymmetric reflectivity characteristics. For an RB of known dimensions, a given value of theta fixes the relative values of dpsi/dt and dphi/dt. In forced precession, the angular momentum precesses about a symmetry axis defined by the relevant torque. However, in LEO, only gravity gradient and magnetic eddy current torques are dominant, and these

  18. Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation.

    Science.gov (United States)

    Djordjevic, Ivan B

    2011-07-18

    In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log2N times better than that of PPM.

  19. Tidal Heating of Earth-like Exoplanets around M Stars: Thermal, Magnetic, and Orbital Evolutions.

    Science.gov (United States)

    Driscoll, P E; Barnes, R

    2015-09-01

    The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low-mass M stars whose radiative habitable zone overlaps with the "tidal zone," where tidal dissipation is expected to be a significant heat source in the interior. We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbital circularization and migration. We illustrate thermal-orbital steady states where surface heat flow is balanced by tidal dissipation and cooling can be stalled for billions of years until circularization occurs. Orbital energy dissipated as tidal heat in the interior drives both inward migration and circularization, with a circularization time that is inversely proportional to the dissipation rate. We identify a peak in the internal dissipation rate as the mantle passes through a viscoelastic state at mantle temperatures near 1800 K. Planets orbiting a 0.1 solar-mass star within 0.07 AU circularize before 10 Gyr, independent of initial eccentricity. Once circular, these planets cool monotonically and maintain dynamos similar to that of Earth. Planets forced into eccentric orbits can experience a super-cooling of the core and rapid core solidification, inhibiting dynamo action for planets in the habitable zone. We find that tidal heating is insignificant in the habitable zone around 0.45 (or larger) solar-mass stars because tidal dissipation is a stronger function of orbital distance than stellar mass, and the habitable zone is farther from larger stars. Suppression of the planetary magnetic field exposes the atmosphere to stellar wind erosion and the surface to harmful radiation. In addition to weak magnetic fields, massive melt eruption rates and prolonged magma oceans may render eccentric planets in the habitable zone of low-mass stars inhospitable for life.

  20. Possible Effect of the Earth's Inertial Induction on the Orbital Decay ...

    Indian Academy of Sciences (India)

    LAGEOS I and II are medium altitude satellites with nearly circular orbits. The motions of these satellites are accurately recorded and the past data of a few decades help to test many theories including the general theory of relativity. Therefore, it is hoped that the effect of the Earth's inertial induction can have any detectable ...

  1. Extension of Earth-Moon libration point orbits with solar sail propulsion

    NARCIS (Netherlands)

    Heiligers, M.J.; Macdonald, Malcolm; Parker, Jeffrey S.

    2016-01-01

    This paper presents families of libration point orbits in the Earth-Moon system that originate from complementing the classical circular restricted three-body problem with a solar sail. Through the use of a differential correction scheme in combination with a continuation on the solar sail

  2. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    DEFF Research Database (Denmark)

    Laundal, Karl M.; Finlay, Chris; Olsen, Nils

    2016-01-01

    analyzed together. In this paper, we present estimates of the average global Birkeland currents and horizontal ionospheric currents from the same set of magnetic field measurements. The magnetic field measurements, from the low Earth orbiting Swarm and CHAMP satellites, are used to co-estimate poloidal...

  3. Seeing Earth's Orbit in the Stars: Parallax and Aberration

    Science.gov (United States)

    Timberlake, Todd K.

    2013-01-01

    During the 17th century the idea of an orbiting and rotating Earth became increasingly popular, but opponents of this view continued to point out that the theory had observable consequences that had never, in fact, been observed. Why, for instance, had astronomers failed to detect the annual parallax of the stars that "must" occur if…

  4. Observing the Polar Upper Atmosphere from Low Earth Orbit: Challenges, Opportunities, and New Missions

    Science.gov (United States)

    Paxton, L. J.

    2001-05-01

    Any observational investigation of a physical phenomenon is confronted with a choice of the temporal and spatial scales to be observed. For observations from a space platform these choices are further constrained by total cost, with its collateral restrictions on payload and instrument size, mass, power, data rate, and choice of orbit. When one posits an investigation of the polar upper atmosphere the choice of orbit is often the determining factor in the design of the instruments. Optical instruments designed for auroral imaging are driven by the desire to image as much of the auroral oval as possible. Choices about bandpasses (the nominal range of sensitivity) have to be made and one commonly encounters far ultraviolet (FUV) instruments. The FUV is chosen because there is no signal from the atmosphere below about 80 km, thus enabling one to make observations of the sunlit aurora. The principle limitations of FUV optical design are the low transmission efficiency of suitable optical materials (glasses and plastics have 0% transmission in the FUV, for example, while commonly used materials have transmissions below 30% for useful thicknesses) and the relatively low reflection efficiency of optical surfaces (this provides a strong impetus towards reducing the total number of reflections since the efficiency if the product of all the reflection efficiencies). From high Earth orbit a camera, that is to say a broadband imager, seems a natural choice as, in principle, such a device can provide continuous imaging at good spatial resolution of the entire oval with reasonable sensitivity. Camera designs have three principle problems: 1) providing a uniform response over the entire image, 2) meeting out of band rejection requirements (i.e. not being sensitive to other than FUV light), and 3) providing images at more than one wavelength simultaneously. These last two problems stem from the use of the combination of filters, mirror coatings, and photocathodes to define the

  5. Space environmental effects on LDEF low Earth orbit exposed graphite reinforced polymer matrix composites

    Science.gov (United States)

    George, Pete

    1992-01-01

    The Long Duration Exposure Facility (LDEF) was deployed on April 7, 1984 in low earth orbit (LEO) at an altitude of 482 kilometers. On board experiments experienced the harsh LEO environment including atomic oxygen (AO), ultraviolet radiation (UV), and thermal cycling. During the 5.8 year mission, the LDEF orbit decayed to 340 kilometers where significantly higher AO concentrations exist. LDEF was retrieved on January 12, 1990 from this orbit. One experiment on board LDEF was M0003, Space Effects on Spacecraft Materials. As a subset of M0003 nearly 500 samples of polymer, metal, and glass matrix composites were flown as the Advanced Composites Experiment M0003-10. The Advanced Composites Experiment is a joint effort between government and industry with the Aerospace Corporation serving as the experiment integrator. A portion of the graphite reinforced polymer matrix composites were furnished by the Boeing Defense and Space Group, Seattle, Washington. Test results and discussions for the Boeing portion of M0003-10 are presented. Experiment and specimen location on the LDEF are presented along with a quantitative summary of the pertinent exposure conditions. Matrix materials selected for the test were epoxy, polysulfone, and polyimide. These composite materials were selected due to their suitability for high performance structural capability in spacecraft applications. Graphite reinforced polymer matrix composites offer higher strength to weight ratios along with excellent dimensional stability. The Boeing space exposed and corresponding ground control composite specimens were subjected to post flight mechanical, chemical, and physical testing in order to determine any changes in critical properties and performance characteristics. Among the more significant findings are the erosive effect of atomic oxygen on leading edge exposed specimens and microcracking in non-unidirectionally reinforced flight specimens.

  6. Low-Thrust Transfer Design of Low-Observable Geostationary Earth Orbit Satellite

    Directory of Open Access Journals (Sweden)

    Bing Hua

    2015-01-01

    Full Text Available With radar and surface-to-air missiles posing an increasing threat to on-orbit spacecraft, low-observable satellites play an important role in low-thrust transfers. This paper presents the design for a low-thrust geostationary earth orbit (GEO transfer control strategy which takes into consideration the low-observable constraint and discusses Earth shadow and perturbation. A control parameter optimization addresses the orbit transfer problem, and five thrust modes are used. Simulation results show that the method outlined in this paper is simple and feasible and results in reduced transfer time with a small amount of calculation. The method therefore offers a useful reference for low-thrust GEO transfer design.

  7. A Small Spacecraft Swarm Deployment and Stationkeeping Strategy for Sun-Earth L1 Halo Orbits

    Science.gov (United States)

    Renea Conn, Tracie; Bookbinder, Jay

    2018-01-01

    Spacecraft orbits about the Sun-Earth librarian point L1 have been of interest since the 1950s. An L1 halo orbit was first achieved with the International Sun-Earth Explorer-3 (ISEE-3) mission, and similar orbits around Sun-Earth L1 were achieved in the Solar and Heliospheric Observatory (SOHO), Advanced Composition Explorer (ACE), Genesis, and Deep Space Climate Observatory (DSCOVR) missions. With recent advancements in CubeSat technology, we envision that it will soon be feasible to deploy CubeSats at L1. As opposed to these prior missions where one large satellite orbited alone, a swarm of CubeSats at L1 would enable novel science data return, providing a topology for intersatellite measurements of heliophysics phenomena both spatially and temporally, at varying spatial scales.The purpose of this iPoster is to present a flight dynamics strategy for a swarm of numerous CubeSats orbiting Sun-Earth L1. The presented method is a coupled, two-part solution. First, we present a deployment strategy for the CubeSats that is optimized to produce prescribed, time-varying intersatellite baselines for the purposes of collecting magnetometer data as well as radiometric measurements from cross-links. Second, we employ a loose control strategy that was successfully applied to SOHO and ACE for minimized stationkeeping propellant expenditure. We emphasize that the presented solution is practical within the current state-of-the-art and heritage CubeSat technology, citing capabilities of CubeSat designs that will launch on the upcoming Exploration Mission 1 (EM-1) to lunar orbits and beyond. Within this iPoster, we present animations of the simulated deployment strategy and resulting spacecraft trajectories. Mission design parameters such as total Δv required for long-term station keeping and minimum/maximum/mean spacecraft separation distances are also presented.

  8. Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond

    Science.gov (United States)

    Cottin, Hervé; Kotler, Julia Michelle; Billi, Daniela; Cockell, Charles; Demets, René; Ehrenfreund, Pascale; Elsaesser, Andreas; d'Hendecourt, Louis; van Loon, Jack J. W. A.; Martins, Zita; Onofri, Silvano; Quinn, Richard C.; Rabbow, Elke; Rettberg, Petra; Ricco, Antonio J.; Slenzka, Klaus; de la Torre, Rosa; de Vera, Jean-Pierre; Westall, Frances; Carrasco, Nathalie; Fresneau, Aurélien; Kawaguchi, Yuko; Kebukawa, Yoko; Nguyen, Dara; Poch, Olivier; Saiagh, Kafila; Stalport, Fabien; Yamagishi, Akihiko; Yano, Hajime; Klamm, Benjamin A.

    2017-07-01

    The space environment is regularly used for experiments addressing astrobiology research goals. The specific conditions prevailing in Earth orbit and beyond, notably the radiative environment (photons and energetic particles) and the possibility to conduct long-duration measurements, have been the main motivations for developing experimental concepts to expose chemical or biological samples to outer space, or to use the reentry of a spacecraft on Earth to simulate the fall of a meteorite. This paper represents an overview of past and current research in astrobiology conducted in Earth orbit and beyond, with a special focus on ESA missions such as Biopan, STONE (on Russian FOTON capsules) and EXPOSE facilities (outside the International Space Station). The future of exposure platforms is discussed, notably how they can be improved for better science return, and how to incorporate the use of small satellites such as those built in cubesat format.

  9. The rotational motion of an earth orbiting gyroscope according to the Einstein theory of general relativity

    Science.gov (United States)

    Hoots, F. R.; Fitzpatrick, P. M.

    1979-01-01

    The classical Poisson equations of rotational motion are used to study the attitude motions of an earth orbiting, rapidly spinning gyroscope perturbed by the effects of general relativity (Einstein theory). The center of mass of the gyroscope is assumed to move about a rotating oblate earth in an evolving elliptic orbit which includes all first-order oblateness effects produced by the earth. A method of averaging is used to obtain a transformation of variables, for the nonresonance case, which significantly simplifies the Poisson differential equations of motion of the gyroscope. Long-term solutions are obtained by an exact analytical integration of the simplified transformed equations. These solutions may be used to predict both the orientation of the gyroscope and the motion of its rotational angular momentum vector as viewed from its center of mass. The results are valid for all eccentricities and all inclinations not near the critical inclination.

  10. Ground Track Acquisition and Maintenance Maneuver Modeling for Low-Earth Orbit Satellite

    Directory of Open Access Journals (Sweden)

    Byoung-Sun Lee

    1997-12-01

    Full Text Available This paper presents a comprehensive analytical approach for determining key maneuver parameters associated with the acquisition and maintenance of the ground track for a low-earth orbit. A livearized model relating changes in the drift rate of the ground track directly to changes in the orbital semi-major axis is also developed. The effect of terrestrial atmospheric drag on the semi-major axis is also explored, being quantified through an analytical expression for the decay rate as a function of density. The non-singular Lagrange planetary equations, further simplified for nearly circular orbits, provide the desired relationships between the corrective in-plane impulsive velocity increments and the corresponding effects on the orbit elements. The resulting solution strategy offers excellent insight into the dynamics affecting the timing, magnitude, and frequency of these maneuvers. Simulations are executed for the ground track acquisition and maintenance maneuver as a pre-flight planning and analysis.

  11. Automatic trajectory planning for low-thrust active removal mission in low-earth orbit

    Science.gov (United States)

    Di Carlo, Marilena; Romero Martin, Juan Manuel; Vasile, Massimiliano

    2017-03-01

    In this paper two strategies are proposed to de-orbit up to 10 non-cooperative objects per year from the region within 800 and 1400 km altitude in Low Earth Orbit (LEO). The underlying idea is to use a single servicing spacecraft to de-orbit several objects applying two different approaches. The first strategy is analogous to the Traveling Salesman Problem: the servicing spacecraft rendezvous with multiple objects in order to physically attach a de-orbiting kit that reduces the perigee of the orbit. The second strategy is analogous to the Vehicle Routing Problem: the servicing spacecraft rendezvous and docks with an object, spirals it down to a lower altitude orbit, undocks, and then spirals up to the next target. In order to maximise the number of de-orbited objects with minimum propellant consumption, an optimal sequence of targets is identified using a bio-inspired incremental automatic planning and scheduling discrete optimisation algorithm. The optimisation of the resulting sequence is realised using a direct transcription method based on an asymptotic analytical solution of the perturbed Keplerian motion. The analytical model takes into account the perturbations deriving from the J2 gravitational effect and the atmospheric drag.

  12. Detection of Dark Electric Matter Objects Falling Out from Earth-Crossing Orbits

    Science.gov (United States)

    Drobyshevski, E. M.

    2005-04-01

    If the DM consists of elementary Planckian black holes, their number (and flux) should be fairly low. If, however, they carry an electric charge corresponding to their mass (up to Ze ≈ 10e), such DArk Electric Matter Objects, daemons, should interact strongly with matter. They should be slowed down somewhat when crossing celestial bodies, build up in them, and in multiple systems, in close lying orbits too (e.g., in Earth-crossing orbits). Capture, say, of a Fe nucleus by a negative daemon releases >100 MeV of energy, i.e., cause ejection of ~10 nucleons. The detector consisting of two ZnS(Ag) scintillation screens stacked one upon the other (four modules 0.25 m2 each) detects at CL > 99% events with a time shift corresponding to velocities V ~ 30-5 km/s (in both down- and upward crossings). Such velocities are typical for objects trapped into helio- and geocentric orbits (with the latter crossing the Earth's surface to become finally confined to its interior). Of particular significance (> 3σ) is a group with V ≈ 10-15 km/s, which is characteristic of objects falling from near-Earth almost circular heliocentric orbits. Their flux is >10-9 cm-2s-1 and varies with P = 0.5 year.

  13. The low earth orbit environment observed using cream and credo

    Science.gov (United States)

    Watson, C. J.; Dyer, C. S.; Truscott, P. R.; Peerless, C. L.; Sims, A. J.; Barth, J. L.

    The Cosmic Radiation Environment and Dosimetry experiment (CREDO) has been operational on board the Advanced Photovoltaics & Electronics Experiment Spacecraft since August 1994. Extensive measurements of cosmic ray linear energy transfer spectra (using data to January 1996) and total dose (using data to November 1994) have been made, and compared with predictions of standard models. Detailed consideration of spacecraft shielding effects have been made. Predictions are shown to overestimate the measured linear energy transfer spectra. The CREAM experiment was flown on STS-63 in the SpaceHab module. Results show penetration of high energy electrons into the SpaceHab module.

  14. The Predicted Growth of the Low Earth Orbit Space Debris Environment: An Assessment of Future Risk for Spacecraft

    Science.gov (United States)

    Krisko, Paula H.

    2007-01-01

    Space debris is a worldwide-recognized issue concerning the safety of commercial, military, and exploration spacecraft. The space debris environment includes both naturally occuring meteoroids and objects in Earth orbit that are generated by human activity, termed orbital debris. Space agencies around the world are addressing the dangers of debris collisions to both crewed and robotic spacecraft. In the United States, the Orbital Debris Program Office at the NASA Johnson Space Center leads the effort to categorize debris, predict its growth, and formulate mitigation policy for the environment from low Earth orbit (LEO) through geosynchronous orbit (GEO). This paper presents recent results derived from the NASA long-term debris environment model, LEGEND. It includes the revised NASA sodium potassium droplet model, newly corrected for a factor of two over-estimation of the droplet population. The study indicates a LEO environment that is already highly collisionally active among orbital debris larger than 1 cm in size. Most of the modeled collision events are non-catastrophic (i.e., They lead to a cratering of the target, but no large scale fragmentation.). But they are potentially mission-ending, and take place between impactors smaller than 10 cm and targets larger than 10 cm. Given the small size of the impactor these events would likely be undetectable by present-day measurement means. The activity continues into the future as would be expected. Impact rates of about four per year are predicted by the current study within the next 30 years, with the majority of targets being abandoned intacts (spent upper stages and spacecraft). Still, operational spacecraft do show a small collisional activity, one that increases over time as the small fragment population increases.

  15. Application of X-Ray Pulsar Navigation: A Characterization of the Earth Orbit Trade Space

    Science.gov (United States)

    Yu, Wayne Hong

    2016-01-01

    The potential for pulsars as a navigation source has been studied since their discovery in 1967. X-ray pulsar navigation (XNAV) is a celestial navigation system that uses the consistent timing nature of x-ray photons from millisecond pulsars (MSP) to perform space navigation. By comparing the detected arrival of x-ray photons to a reference database of expected pulsar light-curve timing models, one can infer a range and range rate measurement based on light time delay. Much of the challenge of XNAV comes from the faint signal, availability, and distant nature of pulsars. This is a study of potential pulsar XNAV measurements to measure extended Kalman filter (EKF) tracking performance with a wide trade space of bounded Earth orbits, using a simulation of existing x-ray detector space hardware. An example of an x-ray detector for XNAV is the NASA Station Explorer for X-ray Timing and Navigation (SEXTANT) mission, a technology demonstration of XNAV set to perform on the International Space Station (ISS) in late 2016early 2017. XNAV hardware implementation is driven by trajectory and environmental influences which add noise to the x-ray pulse signal. In a closed Earth orbit, the radiation environment can exponentially increase the signal noise from x-ray pulsar sources, decreasing the quality and frequency of measurements. The SEXTANT mission in particular improves on the signal to noise ratio by focusing an array of 56 x-ray silicon drift detectors at one pulsar target at a time. This reduces timing glitches and other timing noise contributions from ambient x-ray sources to within a 100 nanosecond resolution. This study also considers the SEXTANT scheduling challenges inherent in a single target observation. Finally, as the navigation sources are now relatively inertial targets, XNAV measurements are also subject to periods of occultation from various celestial bodies. This study focuses on the characterization of these drivers in closed Earth orbits and is not a

  16. The effect of proton radiation on the EMCCD for a low Earth orbit satellite mission

    Science.gov (United States)

    Smith, Ken; Daigle, Olivier; Scott, Alan; Piche, Louis; Hudson, Danya

    2016-08-01

    We report on the proton radiation effects on a 1k x 1k e2v EMCCD utilized in the Nüvü EM N2 1024 camera. Radiation testing was performed at the TRIUMF Proton Irradiation Facility in Canada, where the e2v CCD201-20 EMCCD received a 105 MeV proton fluence up to 5.2x109 protons/cm2, emulating a 1 year's radiation dose of solar protons in low earth orbit with nominal shielding that would be expected from a small or microsatellite. The primary space-based application is for Space Situational Awareness (SSA), where a small telescope images faint orbiting Resident Space Objects (RSOs) on the EMCCD, resulting in faint streaks at the photon level of signal in the images. Of particular concern is the effect of proton radiation on low level CTE, where very low level signals could be severely impaired if not lost. Although other groups have reported on the characteristics of irradiated EMCCDs, their CTE results are not portable to this application. To understand the real impact of proton irradiation the device must be tested under realistic operating conditions with representative backgrounds, clock periods, and signal levels. Testing was performed both in the laboratory and under a night sky on the ground in order to emulate a complex star background environment containing RSOs. The degradation is presented and mitigation techniques are proposed. As compared to conventional CCDs, the EMCCD with high gain allows faint and moving RSOs to be detected with a relatively small telescope aperture, at improved signal to noise ratio at high frame rates. This allows the satellite platform to take sharp images immediately upon slewing to the target without the need for complex and relatively slow attitude stabilization systems.

  17. Orbit/launch vehicle tradeoff studies. Earth Observatory Satellite system definition study (EOS)

    Science.gov (United States)

    1974-01-01

    An evaluation of the Earth Observatory Satellite (EOS) design, performance, and cost factors which affect the choices of an orbit and a launch vehicle is presented. Primary emphasis is given to low altitude (300 to 900 nautical miles) land resources management applications for which payload design factors are defined. The subjects considered are: (1) a mission model, (2) orbit analysis and characterization, (3) characteristics and capabilities of candidate conventional launch vehicles, and space shuttle support. Recommendations are submitted for the EOS-A mission, the Single Multispectral Scanner payload, the Single Multispectral Scanner plus Thematic Mapper payload, the Dual Multispectral Scanner payload, and the Dual Multispectral Scanner plus Thematic Mapper payload.

  18. Uranian ring orbits from earth-based and Voyager occultation observations

    Science.gov (United States)

    French, Richard G.; Elliot, J. L.; French, Linda M.; Kangas, Julie A.; Meech, Karen J.

    1988-01-01

    A novel kinematical model of the Uranian rings has been derived from Voyager occultation timings and earth-based observations of the occultations of U23, U25, and U28, to yield an improved orbit solution that is accurate to about 1 km in the ring plane; this allows a critical comparison to be conducted between ring locations and suspected resonances. The gamma ring is noted to have a peculiar orbit that combines a precessing elliptical ring with a radially-oscillating normal mode. The kinematical model confirms the suspected association of resonances between the 1986U7 and 1986U8 satellites with some of the rings.

  19. High orbital angular momentum harmonic generation

    CERN Document Server

    Vieira, J; Alves, E P; Fonseca, R A; Mendonça, J T; Bingham, R; Norreys, P; Silva, L O

    2016-01-01

    We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realised in any nonlinear optical Kerr media supporting three-wave interactions.

  20. Precision non-conservative force modelling for Low Earth Orbiting spacecraft

    OpenAIRE

    Sibthorpe, Anthony John

    2006-01-01

    Low Earth Orbiting spacecraft are used in various ways for remote observation and measurement of system Earth some classes of measurements are only useful when modelled in a spatial reference frame. As the position of a satellite at a particular epoch is used to provide a fixed point of reference, it is vital that we know these positions both accurately and precisely. Non-conservative forces, which change the energy state of a spacecraft system, can have a dramatic effect on the estimated pos...

  1. Phasing Delta-V for transfers from Sun-Earth halo orbits to the Moon

    Science.gov (United States)

    Chen, Hongru; Kawakatsu, Yasuhiro; Hanada, Toshiya

    2016-10-01

    Inspired by successful extended missions such as the ISEE-3, an investigation for the extended mission that involves a lunar encounter following a Sun-Earth halo orbit mission is considered valuable. Most previous studies present the orbit-to-orbit transfers where the lunar phase is not considered. Intended for extended missions, the present work aims to solve for the minimum phasing ∆V for various initial lunar phases. Due to the solution multiplicity of the two-point boundary value problem, the general constrained optimization algorithm that does not identify multiple feasible solutions is shown to miss minima. A two-step differential corrector with a two-body Lambert solver is developed for identifying multiple solutions. The minimum ∆V associated with the short-way and long-way approaches can be recovered. It is acquired that the required ∆V to cover all initial lunar phases is around 45 m/s for the halo orbit with out-of-plane amplitude Az greater than 3.5×105 km, and 14 m/s for a small halo orbit with Az=1×105 km. In addition, the paper discusses the phasing planning based on the ∆V result and the shift of lunar phase with halo orbit revolution.

  2. Trade Study for Neutron Transport at Low Earth Orbit: Adding Fidelity to DIORAMA

    Energy Technology Data Exchange (ETDEWEB)

    McClanahan, Tucker Caden [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wakeford, Daniel Tyler [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-22

    The Distributed Infrastructure Offering Real-Time Access to Modeling and Analysis (DIORAMA) software provides performance modeling capabilities of the United States Nuclear Detonation Detection System (USNDS) with a focus on the characterization of Space-Based Nuclear Detonation Detection (SNDD) instrument performance [1]. A case study was done to add the neutron propagation capabilities of DIORAMA to low earth orbit (LEO), and compare the back-calculated incident energy from the time-of- ight (TOF) spectrum with the scored incident energy spectrum. As the scoring altitude lowers, the time increase due to scattering takes up much more of the fraction of total TOF; whereas at geosynchronous earth orbit (GEO), the time increase due to scattering is a negligible fraction of the total TOF [2]. The scattering smears out the TOF enough to make the back-calculation of the initial energy spectrum from the TOF spectrum very convoluted.

  3. FLUKA Calculation of the Neutron Albedo Encountered at Low Earth Orbits

    CERN Document Server

    Claret, Arnaud; Combier, Natacha; Ferrari, Alfredo; Laurent, Philippe

    2014-01-01

    This paper presents Monte-Carlo simulations based on the Fluka code aiming to calculate the contribution of the neutron albedo at a given date and altitude above the Earth chosen by the user. The main input parameters of our model are the solar modulation affecting the spectra of cosmic rays, and the date of the Earth’s geomagnetic fi eld. The results consist in a two-parameter distribution, the neutron energy and the angle to the tangent plane of the sphere containing the orbi t of interest, and are provided by geographical position above the E arth at the chosen altitude. This model can be used to predict the te mporal variation of the neutron fl ux encountered along the orbit, and thus constrain the determination of the instrumental backg round noise of space experiments in low earth orbit.

  4. The detection of ultra-relativistic electrons in low Earth orbit

    Science.gov (United States)

    Katsiyannis, Athanassios C.; Dominique, Marie; Pierrard, Viviane; Rosson, Graciela Lopez; Keyser, Johan De; Berghmans, David; Kruglanski, Michel; Dammasch, Ingolf E.; Donder, Erwin De

    2018-01-01

    Aims: To better understand the radiation environment in low Earth orbit (LEO), the analysis of in-situ observations of a variety of particles, at different atmospheric heights, and in a wide range of energies, is needed. Methods: We present an analysis of energetic particles, indirectly detected by the large yield radiometer (LYRA) instrument on board ESA's project for on-board autonomy 2 (PROBA2) satellite as background signal. Combining energetic particle telescope (EPT) observations with LYRA data for an overlapping period of time, we identified these particles as electrons with an energy range of 2 to 8 MeV. Results: The observed events are strongly correlated to geo-magnetic activity and appear even during modest disturbances. They are also well confined geographically within the L = 4-6 McIlwain zone, which makes it possible to identify their source. Conclusions: Although highly energetic particles are commonly perturbing data acquisition of space instruments, we show in this work that ultra-relativistic electrons with energies in the range of 2-8 MeV are detected only at high latitudes, while not present in the South Atlantic Anomaly region.

  5. Radiation Protection Effectiveness of Polymeric Based Shielding Materials at Low Earth Orbit

    Science.gov (United States)

    Badavi, Francis F.; Stewart-Sloan, Charlotte R.; Wilson, John W.; Adams, Daniel O.

    2008-01-01

    Correlations of limited ionizing radiation measurements onboard the Space Transportation System (STS; shuttle) and the International Space Station (ISS) with numerical simulations of charged particle transport through spacecraft structure have indicated that usage of hydrogen rich polymeric materials improves the radiation shielding performance of space structures as compared to the traditionally used aluminum alloys. We discuss herein the radiation shielding correlations between measurements on board STS-81 (Atlantis, 1997) using four polyethylene (PE) spheres of varying radii, and STS-89 (Endeavour, 1998) using aluminum alloy spheres; with numerical simulations of charged particle transport using the Langley Research Center (LaRC)-developed High charge (Z) and Energy TRaNsport (HZETRN) algorithm. In the simulations, the Galactic Cosmic Ray (GCR) component of the ionizing radiation environment at Low Earth Orbit (LEO) covering ions in the 1albedo neutron environment resulting from interaction of GCR ions with upper atmosphere is modeled through extrapolation of the Atmospheric Ionizing Radiation (AIR) measurements. With the validity of numerical simulations through correlation with PE and aluminum spheres measurements established, we further present results from the expansion of the simulations through the selection of high hydrogen content commercially available polymeric constituents such as PE foam core and Spectra fiber(Registered TradeMark) composite face sheet to assess their radiation shield properties as compared to generic PE.

  6. Precision non-conservative force modelling for Low Earth Orbiting spacecraft

    Science.gov (United States)

    Sibthorpe, Anthony John

    2006-10-01

    Low Earth Orbiting spacecraft are used in various ways for remote observation and measurement of system Earth some classes of measurements are only useful when modelled in a spatial reference frame. As the position of a satellite at a particular epoch is used to provide a fixed point of reference, it is vital that we know these positions both accurately and precisely. Non-conservative forces, which change the energy state of a spacecraft system, can have a dramatic effect on the estimated position of a satellite if unmodelled or, as is often the case, are modelled only crudely. Downstream Earth observation data can inherit significant errors as a result. As an example of this, it has been recognised that apparent long wavelength signals can be introduced into interferometric synthetic aperture radar (SAR) images by orbit error. Such images are used to monitor surface deformation, and may provide an indication of strain accumulation as a pre-cursor to Earthquake activity. It makes sense therefore to better model these non-conservative forces, thus improving the quality of the Earth observation data. This project develops precise methodologies for modelling of solar radiation pressure / thermal re-radiation / eclipse modelling / Earth radiation pressure / spacecraft internal heat distribution / on-board instrument power output, and applies these techniques to the European Space Agency's ENVISAT satellite. This complicated satellite has necessitated the development of a significant number of new algorithms for dealing with a large number of geometric primitives. A graphical display tool, developed during this research, allows rapid model development and improved error checking. Resultant models are incorporated into the GEODYN II orbit determination software, developed at NASA's Goddard Space Flight Centre. Precise orbits computed using tracking data in combination with the newly developed force models are compared against precise orbits generated using nominal force

  7. An Integrated Approach to Modeling Solar Electric Propulsion Vehicles During Long Duration, Near-Earth Orbit Transfers

    Science.gov (United States)

    Smith, David A.; Hojnicki, Jeffrey S.; Sjauw, Waldy K.

    2014-01-01

    Recent NASA interest in utilizing solar electronic propulsion (SEP) technology to transfer payloads, e.g. from low-Earth orbit (LEO) to higher energy geostationary-Earth orbit (GEO) or to Earth escape, has necessitated the development of high fidelity SEP vehicle models and simulations. These models and simulations need to be capable of capturing vehicle dynamics and sub-system interactions experienced during the transfer trajectories which are typically accomplished with continuous-burn (potentially interrupted by solar eclipse), long duration "spiral out" maneuvers taking several months or more to complete. This paper presents details of an integrated simulation approach achieved by combining a high fidelity vehicle simulation code with a detailed solar array model. The combined simulation tool gives researchers the functionality to study the integrated effects of various vehicle sub-systems (e.g. vehicle guidance, navigation and control (GN&C), electric propulsion system (EP)) with time varying power production. Results from a simulation model of a vehicle with a 50 kW class SEP system using the integrated tool are presented and compared to the results from another simulation model employing a 50 kW end-of-life (EOL) fixed power level assumption. These models simulate a vehicle under three degree of freedom dynamics (i.e. translational dynamics only) and include the effects of a targeting guidance algorithm (providing a "near optimal" transfer) during a LEO to near Earth escape (C (sub 3) = -2.0 km (sup 2) / sec (sup -2) spiral trajectory. The presented results include the impact of the fully integrated, time-varying solar array model (e.g. cumulative array degradation from traversing the Van Allen belts, impact of solar eclipses on the vehicle and the related temperature responses in the solar arrays due to operating in the Earth's thermal environment, high fidelity array power module, etc.); these are used to assess the impact on vehicle performance (i

  8. Halo orbit transfer trajectory design using invariant manifold in the Sun-Earth system accounting radiation pressure and oblateness

    Science.gov (United States)

    Srivastava, Vineet K.; Kumar, Jai; Kushvah, Badam Singh

    2018-01-01

    In this paper, we study the invariant manifold and its application in transfer trajectory problem from a low Earth parking orbit to the Sun-Earth L1 and L2-halo orbits with the inclusion of radiation pressure and oblateness. Invariant manifold of the halo orbit provides a natural entrance to travel the spacecraft in the solar system along some specific paths due to its strong hyperbolic character. In this regard, the halo orbits near both collinear Lagrangian points are computed first. The manifold's approximation near the nominal halo orbit is computed using the eigenvectors of the monodromy matrix. The obtained local approximation provides globalization of the manifold by applying backward time propagation to the governing equations of motion. The desired transfer trajectory well suited for the transfer is explored by looking at a possible intersection between the Earth's parking orbit of the spacecraft and the manifold.

  9. Econometric comparisons of liquid rocket engines for dual-fuel advanced earth-to-orbit shuttles

    Science.gov (United States)

    Martin, J. A.

    1978-01-01

    Econometric analyses of advanced Earth-to-orbit vehicles indicate that there are economic benefits from development of new vehicles beyond the space shuttle as traffic increases. Vehicle studies indicate the advantage of the dual-fuel propulsion in single-stage vehicles. This paper shows the economic effect of incorporating dual-fuel propulsion in advanced vehicles. Several dual-fuel propulsion systems are compared to a baseline hydrogen and oxygen system.

  10. Preliminary design and analysis of large delta wings for earth-to-orbit transports

    Science.gov (United States)

    Lemessurier, R. W.; Bailey, J. P.; Macconochie, I. O.

    1979-01-01

    Two studies are described in which CAD methods are used for preliminary design of advanced earth-to-orbit transport wings. The first structural concept was a multilayer honeycomb wing composed of diffusion-bonded Inconel 718; the second concept (in which structural simplicity was sought) involved a honeycomb sandwich wing, for which only a leading edge and trailing edge spar were used. Some new technologies applicable to advanced wing designs are briefly discussed.

  11. Prevalence of Earth-size Planets Orbiting Sun-like Stars

    Science.gov (United States)

    Petigura, Erik Ardeshir

    2015-04-01

    In this thesis, I explore two topics in exoplanet science. The first is the prevalence of Earth-size planets in the Milky Way Galaxy. To determine the occurrence of planets having different sizes, orbital periods, and other properties, I conducted a survey of extrasolar planets using data collected by NASA's Kepler Space Telescope. This project involved writing new algorithms to analyze Kepler data, finding planets, and conducting follow-up work using ground-based telescopes. I found that most stars have at least one planet at or within Earth's orbit and that 26% of Sun-like stars have an Earth-size planet with an orbital period of 100 days or less. The second topic is the connection between the properties of planets and their host stars. The precise characterization of exoplanet hosts helps to bring planet properties like mass, size, and equilibrium temperature into sharper focus and probes the physical processes that form planets. I studied the abundance of carbon and oxygen in over 1000 nearby stars using optical spectra taken by the California Planet Search. I found a large range in the relative abundance of carbon and oxygen in this sample, including a handful of carbon-rich stars. I also developed a new technique called SpecMatch for extracting fundamental stellar parameters from optical spectra. SpecMatch is particularly applicable to the relatively faint planet-hosting stars discovered by Kepler.

  12. Technology Development to Support Human Health and Performance in Exploration Beyond Low Earth Orbit

    Science.gov (United States)

    Kundrot, C.E.; Steinberg, S. L.; Charles, J. B.

    2011-01-01

    In the course of defining the level of risks and mitigating the risks for exploration missions beyond low Earth orbit, NASA s Human Research Program (HRP) has identified the need for technology development in several areas. Long duration missions increase the risk of serious medical conditions due to limited options for return to Earth; no resupply; highly limited mass, power, volume; and communication delays. New space flight compatible medical capabilities required include: diagnostic imaging, oxygen concentrator, ventilator, laboratory analysis (saliva, blood, urine), kidney stone diagnosis & treatment, IV solution preparation and delivery. Maintenance of behavioral health in such an isolated, confined and extreme environment requires new sensory stimulation (e.g., virtual reality) technology. Unobtrusive monitoring of behavioral health and treatment methods are also required. Prolonged exposure to weightlessness deconditions bone, muscle, and the cardiovascular system. Novel exercise equipment or artificial gravity are necessary to prevent deconditioning. Monitoring of the degree of deconditioning is required to ensure that countermeasures are effective. New technologies are required in all the habitable volumes (e.g., suit, capsule, habitat, exploration vehicle, lander) to provide an adequate food system, and to meet human environmental standards for air, water, and surface contamination. Communication delays require the crew to be more autonomous. Onboard decision support tools that assist crew with real-time detection and diagnosis of vehicle and habitat operational anomalies will enable greater autonomy. Multi-use shield systems are required to provide shielding from solar particle events. The HRP is pursuing the development of these technologies in laboratories, flight analog environments and the ISS so that the human health and performance risks will be acceptable with the available resources.

  13. Comparison of technologies for deorbiting spacecraft from low-earth-orbit at end of mission

    Science.gov (United States)

    Sánchez-Arriaga, G.; Sanmartín, J. R.; Lorenzini, E. C.

    2017-09-01

    An analytical comparison of four technologies for deorbiting spacecraft from Low-Earth-Orbit at end of mission is presented. Basic formulas based on simple physical models of key figures of merit for each device are found. Active devices - rockets and electrical thrusters - and passive technologies - drag augmentation devices and electrodynamic tethers - are considered. A basic figure of merit is the deorbit device-to-spacecraft mass ratio, which is, in general, a function of environmental variables, technology development parameters and deorbit time. For typical state-of-the-art values, equal deorbit time, middle inclination and initial altitude of 850 km, the analysis indicates that tethers are about one and two orders of magnitude lighter than active technologies and drag augmentation devices, respectively; a tether needs a few percent mass-ratio for a deorbit time of a couple of weeks. For high inclination, the performance drop of the tether system is moderate: mass ratio and deorbit time increase by factors of 2 and 4, respectively. Besides collision risk with other spacecraft and system mass considerations, such as main driving factors for deorbit space technologies, the analysis addresses other important constraints, like deorbit time, system scalability, manoeuver capability, reliability, simplicity, attitude control requirement, and re-entry and multi-mission capability (deorbit and re-boost) issues. The requirements and constraints are used to make a critical assessment of the four technologies as functions of spacecraft mass and initial orbit (altitude and inclination). Emphasis is placed on electrodynamic tethers, including the latest advances attained in the FP7/Space project BETs. The superiority of tape tethers as compared to round and multi-line tethers in terms of deorbit mission performance is highlighted, as well as the importance of an optimal geometry selection, i.e. tape length, width, and thickness, as function of spacecraft mass and initial

  14. Minimum fuel round trip from a $L_2$ Earth-Moon Halo orbit to Asteroid 2006 RH$_{120}$

    OpenAIRE

    Chyba, Monique; Haberkorn, Thomas; Jedicke, Robert

    2016-01-01

    International audience; The goal of this paper is to design a spacecraft round trip transfer from a parking orbit to Asteroid 2006\\;RH$_{120}$, during its capture time by Earth's gravity, while maximizing the final mass or equivalently minimizing the delta-v. The parking orbit is chosen as a Halo orbit around the Earth-Moon $L_2$ libration point. The round-trip transfer is composed of three portions: a rendezvous transfer departing from the parking orbit to reach 2006\\;RH$_{120}$, a lock-in p...

  15. Space Radiation: The Number One Risk to Astronaut Health beyond Low Earth Orbit

    Directory of Open Access Journals (Sweden)

    Jeffery C. Chancellor

    2014-09-01

    Full Text Available Projecting a vision for space radiobiological research necessitates understanding the nature of the space radiation environment and how radiation risks influence mission planning, timelines and operational decisions. Exposure to space radiation increases the risks of astronauts developing cancer, experiencing central nervous system (CNS decrements, exhibiting degenerative tissue effects or developing acute radiation syndrome. One or more of these deleterious health effects could develop during future multi-year space exploration missions beyond low Earth orbit (LEO. Shielding is an effective countermeasure against solar particle events (SPEs, but is ineffective in protecting crew members from the biological impacts of fast moving, highly-charged galactic cosmic radiation (GCR nuclei. Astronauts traveling on a protracted voyage to Mars may be exposed to SPE radiation events, overlaid on a more predictable flux of GCR. Therefore, ground-based research studies employing model organisms seeking to accurately mimic the biological effects of the space radiation environment must concatenate exposures to both proton and heavy ion sources. New techniques in genomics, proteomics, metabolomics and other “omics” areas should also be intelligently employed and correlated with phenotypic observations. This approach will more precisely elucidate the effects of space radiation on human physiology and aid in developing personalized radiological countermeasures for astronauts.

  16. Space Radiation: The Number One Risk to Astronaut Health beyond Low Earth Orbit

    Science.gov (United States)

    Chancellor, Jeffery C.; Scott, Graham B. I.; Sutton, Jeffrey P.

    2014-01-01

    Projecting a vision for space radiobiological research necessitates understanding the nature of the space radiation environment and how radiation risks influence mission planning, timelines and operational decisions. Exposure to space radiation increases the risks of astronauts developing cancer, experiencing central nervous system (CNS) decrements, exhibiting degenerative tissue effects or developing acute radiation syndrome. One or more of these deleterious health effects could develop during future multi-year space exploration missions beyond low Earth orbit (LEO). Shielding is an effective countermeasure against solar particle events (SPEs), but is ineffective in protecting crew members from the biological impacts of fast moving, highly-charged galactic cosmic radiation (GCR) nuclei. Astronauts traveling on a protracted voyage to Mars may be exposed to SPE radiation events, overlaid on a more predictable flux of GCR. Therefore, ground-based research studies employing model organisms seeking to accurately mimic the biological effects of the space radiation environment must concatenate exposures to both proton and heavy ion sources. New techniques in genomics, proteomics, metabolomics and other “omics” areas should also be intelligently employed and correlated with phenotypic observations. This approach will more precisely elucidate the effects of space radiation on human physiology and aid in developing personalized radiological countermeasures for astronauts. PMID:25370382

  17. The Lunar Space Tug: A sustainable bridge between low Earth orbits and the Cislunar Habitat

    Science.gov (United States)

    Mammarella, M.; Paissoni, C. A.; Viola, N.; Denaro, A.; Gargioli, E.; Massobrio, F.

    2017-09-01

    The International Space Station is the first space human outpost and over the last 15 years, it has represented a peculiar environment where science, technology and human innovation converge together in a unique microgravity and space research laboratory. With the International Space Station entering the second part of its life and its operations running steadily at nominal pace, the global space community is starting planning how the human exploration could move further, beyond Low-Earth-Orbit. According to the Global Exploration Roadmap, the Moon represents the next feasible path-way for advances in human exploration towards the nal goal, Mars. Based on the experience of the ISS, one of the most widespread ideas is to develop a Cislunar Station in preparation of long duration missions in a deep space environment. Cislunar space is de ned as the area of deep space under the influence of Earth-Moon system, including a set of special orbits, e.g. Earth-Moon Libration points and Lunar Retrograde Orbit. This habitat represents a suitable environment for demonstrating and testing technologies and capabilities in deep space. In order to achieve this goal, there are several crucial systems and technologies, in particular related to transportation and launch systems. The Orion Multi-Purpose Crew Vehicle is a reusable transportation capsule designed to provide crew transportation in deep space missions, whereas NASA is developing the Space Launch System, the most powerful rocket ever built, which could provide the necessary heavy-lift launch capability to support the same kind of missions. These innovations would allow quite-fast transfers from Earth to the Cislunar Station and vice versa, both for manned and unmanned missions. However, taking into account the whole Concept of Operations for both the growth and sustainability of the Cislunar Space Station, the Lunar Space Tug can be considered as an additional, new and fundamental element for the mission architecture. The

  18. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    CERN Document Server

    Laundal, Karl M; Olsen, Nils

    2016-01-01

    Interaction between the solar wind and the Earth's magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horizontally. These current systems are tightly linked, but their global behaviors are rarely analyzed together. In this paper, we present estimates of the average global Birkeland currents and horizontal ionospheric currents from the same set of magnetic field measurements. The magnetic field measurements, from the low Earth orbiting $\\textit{Swarm}$ and CHAMP satellites, are used to co-estimate poloidal and toroidal parts of the magnetic disturbance field, represented in magnetic apex coordinates. The use of apex coordinates reduces effects of longitudinal and hemispheric variations in the Earth's main field. We present global currents from both hemispheres during different sunlight conditions. The results show that the Birkeland currents vary with the conductivity, which depends most strongly on solar EUV ...

  19. Properties of an Earth-like planet orbiting a Sun-like star: Earth observed by the EPOXI mission.

    Science.gov (United States)

    Livengood, Timothy A; Deming, L Drake; A'hearn, Michael F; Charbonneau, David; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Meadows, Victoria S; Robinson, Tyler D; Seager, Sara; Wellnitz, Dennis D

    2011-11-01

    NASA's EPOXI mission observed the disc-integrated Earth and Moon to test techniques for reconnoitering extrasolar terrestrial planets, using the Deep Impact flyby spacecraft to observe Earth at the beginning and end of Northern Hemisphere spring, 2008, from a range of ∼1/6 to 1/3 AU. These observations furnish high-precision and high-cadence empirical photometry and spectroscopy of Earth, suitable as "ground truth" for numerically simulating realistic observational scenarios for an Earth-like exoplanet with finite signal-to-noise ratio. Earth was observed at near-equatorial sub-spacecraft latitude on 18-19 March, 28-29 May, and 4-5 June (UT), in the range of 372-4540 nm wavelength with low visible resolving power (λ/Δλ=5-13) and moderate IR resolving power (λ/Δλ=215-730). Spectrophotometry in seven filters yields light curves at ∼372-948 nm filter-averaged wavelength, modulated by Earth's rotation with peak-to-peak amplitude of ≤20%. The spatially resolved Sun glint is a minor contributor to disc-integrated reflectance. Spectroscopy at 1100-4540 nm reveals gaseous water and carbon dioxide, with minor features of molecular oxygen, methane, and nitrous oxide. One-day changes in global cloud cover resulted in differences between the light curve beginning and end of ≤5%. The light curve of a lunar transit of Earth on 29 May is color-dependent due to the Moon's red spectrum partially occulting Earth's relatively blue spectrum. The "vegetation red edge" spectral contrast observed between two long-wavelength visible/near-IR bands is ambiguous, not clearly distinguishing between the verdant Earth diluted by cloud cover versus the desolate mineral regolith of the Moon. Spectrophotometry in at least one other comparison band at short wavelength is required to distinguish between Earth-like and Moon-like surfaces in reconnaissance observations. However, measurements at 850 nm alone, the high-reflectance side of the red edge, could be sufficient to

  20. Trapped Proton Environment in Medium-Earth Orbit (2000-2010)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yue [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Friedel, Reinhard Hans [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kippen, Richard Marc [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-31

    This report describes the method used to derive fluxes of the trapped proton belt along the GPS orbit (i.e., a Medium-Earth Orbit) during 2000 – 2010, a period almost covering a solar cycle. This method utilizes a newly developed empirical proton radiation-belt model, with the model output scaled by GPS in-situ measurements, to generate proton fluxes that cover a wide range of energies (50keV- 6MeV) and keep temporal features as well. The new proton radiation-belt model is developed based upon CEPPAD proton measurements from the Polar mission (1996 – 2007). Comparing to the de-facto standard empirical model of AP8, this model is not only based upon a new data set representative of the proton belt during the same period covered by GPS, but can also provide statistical information of flux values such as worst cases and occurrence percentiles instead of solely the mean values. The comparison shows quite different results from the two models and suggests that the commonly accepted error factor of 2 on the AP8 flux output over-simplifies and thus underestimates variations of the proton belt. Output fluxes from this new model along the GPS orbit are further scaled by the ns41 in-situ data so as to reflect the dynamic nature of protons in the outer radiation belt at geomagnetically active times. Derived daily proton fluxes along the GPS ns41 orbit, whose data files are delivered along with this report, are depicted to illustrate the trapped proton environment in the Medium-Earth Orbit. Uncertainties on those daily proton fluxes from two sources are evaluated: One is from the new proton-belt model that has error factors < ~3; the other is from the in-situ measurements and the error factors could be ~ 5.

  1. The mass of the super-Earth orbiting the brightest Kepler planet hosting star

    Science.gov (United States)

    Lopez-Morales, Mercedes; HARPS-N Team

    2016-01-01

    HD 179070, aka Kepler-21, is a V = 8.25 oscillating F6IV star and the brightest exoplanet host discovered by Kepler. An early analysis of the Q0 - Q5 Kepler light curves by Howell et al. (2012) revealed transits of a planetary companion, Kepler-21b, with a radius of 1.6 R_Earth and an orbital period of 2.7857 days. However, they could not determine the mass of the planet from the initial radial velocity observations with Keck-HIRES, and were only able to impose a 2s upper limit of about 10 M_Earth. Here we present 82 new radial velocity observations of this system obtained with the HARPS-N spectrograph. We detect the Doppler shift signal of Kepler-21b at the 3.6s level, and measure a planetary mass of 5.9 ± 1.6 M_Earth. We also update the radius of the planet to 1.65 ± 0.08 R_Earth, using the now available Kepler Q0 - Q17 photometry for this target. The mass of Kepler-21b appears to fall on the apparent dividing line between super-Earths that have lost all the material in their outer layers and those that have retained a significant amount of volatiles. Based on our results Kepler-21b belongs to the first group. Acknowledgement: This work was supported by funding from the NASA XRP Program and the John Templeton Foundation.

  2. High-order harmonic generation from eld-distorted orbitals

    DEFF Research Database (Denmark)

    Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer

    We investigate the eect on high-order harmonic generation of the distortion of molecular orbitals by the driving laser eld. Calculations for high-order harmonic generation including orbital distortion are performed for N2 (high polarizability). Our results allow us to suggest that field...... of the minimum in the high-order harmonic spectra. This is in agreement with experiment....

  3. THE HABITABILITY AND DETECTION OF EARTH-LIKE PLANETS ORBITING COOL WHITE DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Fossati, L.; Haswell, C. A.; Patel, M. R.; Busuttil, R. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Bagnulo, S. [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom); Kowalski, P. M. [GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam (Germany); Shulyak, D. V. [Institute of Astrophysics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Sterzik, M. F., E-mail: l.fossati@open.ac.uk, E-mail: C.A.Haswell@open.ac.uk, E-mail: M.R.Patel@open.ac.uk, E-mail: r.busuttil@open.ac.uk, E-mail: sba@arm.ac.uk, E-mail: kowalski@gfz-potsdam.de, E-mail: denis.shulyak@gmail.com, E-mail: msterzik@eso.org [European Southern Observatory, Casilla 19001, Santiago 19 (Chile)

    2012-09-20

    Since there are several ways planets can survive the giant phase of the host star, we examine the habitability and detection of planets orbiting white dwarfs. As a white dwarf cools from 6000 K to 4000 K, a planet orbiting at 0.01 AU would remain in the continuous habitable zone (CHZ) for {approx}8 Gyr. We show that photosynthetic processes can be sustained on such planets. The DNA-weighted UV radiation dose for an Earth-like planet in the CHZ is less than the maxima encountered on Earth, and hence non-magnetic white dwarfs are compatible with the persistence of complex life. Polarization due to a terrestrial planet in the CHZ of a cool white dwarf (CWD) is 10{sup 2} (10{sup 4}) times larger than it would be in the habitable zone of a typical M-dwarf (Sun-like star). Polarimetry is thus a viable way to detect close-in rocky planets around white dwarfs. Multi-band polarimetry would also allow us to reveal the presence of a planet atmosphere, providing a first characterization. Planets in the CHZ of a 0.6 M{sub Sun} white dwarf will be distorted by Roche geometry, and a Kepler-11d analog would overfill its Roche lobe. With current facilities a super-Earth-sized atmosphereless planet is detectable with polarimetry around the brightest known CWD. Planned future facilities render smaller planets detectable, in particular by increasing the instrumental sensitivity in the blue.

  4. Energy Balance and Power Performance Analysis for Satellite in Low Earth Orbit

    Directory of Open Access Journals (Sweden)

    Sung-Soo Jang

    2010-09-01

    Full Text Available The electrical power system (EPS of Korean satellites in low-earth-orbit is designed to achieve energy balance based on a one-orbit mission scenario. This means that the battery has to be fully charged at the end of a one-orbit mission. To provide the maximum solar array (SA power generation, the peak power tracking (PPT method has been developed for a spacecraft power system. The PPT is operated by a software algorithm, which tracks the peak power of the SA and ensures the battery is fully charged in one orbit. The EPS should be designed to avoid the stress of electronics in order to handle the main bus power from the SA power. This paper summarizes the results of energy balance to achieve optimal power sizing and the actual trend analysis of EPS performance in orbit. It describes the results of required power for the satellite operation in the worst power conditions at the end-of-life, the methods and input data used in the energy balance, and the case study of energy balance analyses for the normal operation in orbit. Both 10:35 AM and 10:50 AM crossing times are considered, so the power performance in each case is analyzed with the satellite roll maneuver according to the payload operation concept. In addition, the data transmission to the Korea Ground Station during eclipse is investigated at the local-time-ascending-node of 11:00 AM to assess the greatest battery depth-of-discharge in normal operation.

  5. Radiation Protection Effectiveness of Polymeric Based Shielding Materials at Low Earth Orbit

    Science.gov (United States)

    Badavi, Francis F.; Stewart-Sloan, Charlotte R.; Wilson, John W.; Adams, Daniel O.

    2008-01-01

    Correlations of limited ionizing radiation measurements onboard the Space Transportation System (STS; shuttle) and the International Space Station (ISS) with numerical simulations of charged particle transport through spacecraft structure have indicated that usage of hydrogen rich polymeric materials improves the radiation shielding performance of space structures as compared to the traditionally used aluminum alloys. We discuss herein the radiation shielding correlations between measurements on board STS-81 (Atlantis, 1997) using four polyethylene (PE) spheres of varying radii, and STS-89 (Endeavour, 1998) using aluminum alloy spheres; with numerical simulations of charged particle transport using the Langley Research Center (LaRC)-developed High charge (Z) and Energy TRaNsport (HZETRN) algorithm. In the simulations, the Galactic Cosmic Ray (GCR) component of the ionizing radiation environment at Low Earth Orbit (LEO) covering ions in the 1< or equals Z< or equals 28 range is represented by O'Neill's (2004) model. To compute the transmission coefficient for GCR ions at LEO, O'Neill's model is coupled with the angular dependent LaRC cutoff model. The trapped protons/electrons component of LEO environment is represented by a LaRC-developed time dependent procedure which couples the AP8min/AP8max, Deep River Neutron Monitor (DRNM) and F10.7 solar radio frequency measurements. The albedo neutron environment resulting from interaction of GCR ions with upper atmosphere is modeled through extrapolation of the Atmospheric Ionizing Radiation (AIR) measurements. With the validity of numerical simulations through correlation with PE and aluminum spheres measurements established, we further present results from the expansion of the simulations through the selection of high hydrogen content commercially available polymeric constituents such as PE foam core and Spectra fiber(Registered TradeMark) composite face sheet to assess their radiation shield properties as compared to

  6. May 2005 Halo CMEs and Galactic Cosmic Ray Flux Changes at Earth's Orbit

    Science.gov (United States)

    Ahluwalia, H. S.; Alania, M. V.; Wawrzynczak, A.; Ygbuhay, R. C.; Fikani, M. M.

    2014-05-01

    The pressure corrected hourly data from the global network of cosmic ray detectors, measurements of the interplanetary magnetic field (IMF) intensity ( B) at Earth's orbit and its components B x , B y , B z (in the geocentric solar ecliptic coordinates) are used to conduct a comprehensive study of the galactic cosmic ray (GCR) intensity fluctuations caused by the halo coronal mass ejection of 13 May 2005. Distinct differences exist in GCR timelines recorded by neutron monitors (NMs) and multidirectional muon telescopes (MTs), the latter respond to the high rigidity portion of the GCR differential rigidity spectrum. The Forbush decrease (FD) onset in MTs is delayed (˜5 h) with respect to the onset of a geomagnetic storm sudden commencement (SSC) and a large pre-increase is present in MT data before, during, and after the SSC onset, of unknown origin. The rigidity spectrum, for a range of GCR rigidities (≤200 GV), is a power law in rigidity (R) with a negative exponent ( γ=-1.05) at GCR minimum intensity, leading us to infer that the quasi-linear theory of modulation is inconsistent with observations at high rigidities (>1 GV); the results support the force field theory of modulation. At present, we do not have a comprehensive model for the FD explaining quantitatively all the observational features but we present a preliminary model listing physical processes that may contribute to a FD timeline. We explored the connections between different phases of the FD and the power spectra of IMF components but did not find a sustained relationship.

  7. Mass driver reaction engine characteristics and performance in earth orbital transfer missions

    Science.gov (United States)

    Snow, W. R.; Dunbar, R. S.

    1982-01-01

    Configurations of a typical mass driver reaction engine (MDRE) are presented and its use for delivery of payloads to geosynchronous orbit (GEO) from low earth orbit (LEO) is discussed. Basic rocket equations are developed for LEO to GEO round-trip missions using a single exhaust velocity. It is shown that exhaust velocities in the 5-10 km/sec range (specific impulse of 500-1000 sec) are well suited for mass drivers, minimizing the overall cost of missions. Payload delivery rate fractions show that there is little to be gained by stretching out LEO to GEO transfer times from 90 to 180 days. It therefore pays to use the shorter trip time, approximately doubling the amount of delivered payload during any fixed time of use of the MDRE.

  8. Instrumental background in gamma-ray spectrometers flown in low earth orbit

    Science.gov (United States)

    Gehrels, Neil

    1992-01-01

    Techniques are presented for calculating the instrumental continuum background in gamma-ray spectrometers flown in low earth orbit (LEO), with special attention given to simple methods developed for scaling from the better-understood measurements and calculations of background in balloon-borne instruments to LEO (Gehrels, 1985). Results are presented in the form of predictions of the background and its components for spectrometers in LEO. These predictions are compared to the measured background for the HEAO 3 gamma-ray spectrometer (Mahoney et al., 1980), and predictions are made for the International Gamma-Ray Astrophysics Laboratory mission and the Nuclear Astrophysics Explorer (Matteson et al., 1990) spectrometers. A comparison is made of various orbit options. It is shown that a critical factor is the number of times the instrument passes through the South Atlantic Anomaly (which is the region of enhanced trapped particle fluxes in LEO) and the depth of penetration on each pass.

  9. A real-time guidance algorithm for aerospace plane optimal ascent to low earth orbit

    Science.gov (United States)

    Calise, A. J.; Flandro, G. A.; Corban, J. E.

    1989-01-01

    Problems of onboard trajectory optimization and synthesis of suitable guidance laws for ascent to low Earth orbit of an air-breathing, single-stage-to-orbit vehicle are addressed. A multimode propulsion system is assumed which incorporates turbojet, ramjet, Scramjet, and rocket engines. An algorithm for generating fuel-optimal climb profiles is presented. This algorithm results from the application of the minimum principle to a low-order dynamic model that includes angle-of-attack effects and the normal component of thrust. Maximum dynamic pressure and maximum aerodynamic heating rate constraints are considered. Switching conditions are derived which, under appropriate assumptions, govern optimal transition from one propulsion mode to another. A nonlinear transformation technique is employed to derived a feedback controller for tracking the computed trajectory. Numerical results illustrate the nature of the resulting fuel-optimal climb paths.

  10. Effects of CubeSat Deployments in Low-Earth Orbit

    Science.gov (United States)

    Matney, M. J.; Vavrin, A. B.; Manis, A. P.

    2017-01-01

    Long-term models, such as NASA's LEGEND (LEO (Low-Earth Orbit)-to-GEO (Geosynchrous Earth Orbit) Environment Debris) model, are used to make predictions about how space activities will affect the long-term evolution of the debris environment. Part of this process is to predict how spacecraft and rocket bodies will be launched and left in the environment in the future. This has usually been accomplished by repeating past launch history to simulate future launches. It was partially upon the basis of the results of such models that both national and international orbital debris mitigation guidelines - especially the "25-year rule" for post-mission disposal - were determined. The proliferation of Cubesat launches in recent years, however, has raised concerns that we are seeing a fundamental shift in how humans launch satellites into space that may alter the assumptions upon which our current mitigation guidelines are based. The large number of Cubesats, and their short lifetime and general inability to perform collision avoidance, potentially makes them an important new source of debris. The NASA Orbital Debris Program Office (ODPO) has conducted a series of LEGEND computations to investigate the long-term effects of adding Cubesats to the environment. Several possible future scenarios were simulated to investigate the effects of the size of future Cubesat launches and the efficiency of post-mission disposal on the proliferation of catastrophic collisions over the next 200 years. These results are compared to a baseline "business-as-usual" scenario where launches are assumed to continue as in the past without major Cubesat deployments. Using these results, we make observations about the continued use of the 25-year rule and the importance of the universal application of post-mission disposal. We also discuss how the proliferation of Cubesats may affect satellite traffic at lower altitudes.

  11. Radiation Information for Designing and Interpreting Biological Experiments Onboard Missions Beyond Low Earth Orbit

    Science.gov (United States)

    Straume, T.; Slaba, T.; Bhattacharya, S.; Braby, L. A.

    2017-01-01

    There is growing interest in flying biological experiments beyond low-Earth orbit (LEO) to measure biological responses potentially relevant to those expected during a human mission to Mars. Such experiments could be payloads onboard precursor missions, including unmanned private-public partnerships, as well as small low-cost spacecraft (satellites) designed specifically for biosentinel type missions. Designing such experiments requires knowledge of the radiation environment and its interactions with both the spacecraft and the experimental payload. Information is provided here that is useful for designing such experiments.

  12. An optimum organizational structure for a large earth-orbiting multidisciplinary Space Base

    Science.gov (United States)

    Ragusa, J. M.

    1973-01-01

    The purpose of this exploratory study was to identify an optimum hypothetical organizational structure for a large earth-orbiting multidisciplinary research and applications (R&A) Space Base manned by a mixed crew of technologists. Since such a facility does not presently exist, in situ empirical testing was not possible. Study activity was, therefore, concerned with the identification of a desired organizational structural model rather than the empirical testing of it. The essential finding of this research was that a four-level project type 'total matrix' model will optimize the efficiency and effectiveness of Space Base technologists.

  13. Space Network IP Services (SNIS): An Architecture for Supporting Low Earth Orbiting IP Satellite Missions

    Science.gov (United States)

    Israel, David J.

    2005-01-01

    The NASA Space Network (SN) supports a variety of missions using the Tracking and Data Relay Satellite System (TDRSS), which includes ground stations in White Sands, New Mexico and Guam. A Space Network IP Services (SNIS) architecture is being developed to support future users with requirements for end-to-end Internet Protocol (IP) communications. This architecture will support all IP protocols, including Mobile IP, over TDRSS Single Access, Multiple Access, and Demand Access Radio Frequency (RF) links. This paper will describe this architecture and how it can enable Low Earth Orbiting IP satellite missions.

  14. Adaptive Terminal Sliding Mode Control of Electromagnetic Spacecraft Formation Flying in Near-Earth Orbits

    Directory of Open Access Journals (Sweden)

    Jingrui Zhang

    2014-02-01

    Full Text Available An adaptive terminal sliding mode control for six-degree-of-freedom electromagnetic spacecraft formation flying (EMFF in near-Earth orbits is presented. By using terminal sliding mode (TSM technique, the output tracking error can converge to zero in finite time, and strong robustness with respect to disturbance forces can be guaranteed. Based on a rotated frame Fr and the adaptive TSM controller, the special magnetic moment of the steerable magnetic dipole is computed. The angular momentum management strategy (AMM is implemented in a periodically switching fashion, by which the angular momentum buildup was limited. Illustrative simulations of EMFF are conducted to verify the effectiveness of the proposed controller.

  15. An analysis of propulsion options for transport of lunar materials to earth orbit

    Science.gov (United States)

    Frisbee, R. H.; Jones, R. M.

    1983-01-01

    This paper describes the results of analyses of space-based transportation systems for the transport of extraterrestrial materials from their point of origin on the lunar surface to final delivery point in earth orbit and transport of equipment and supplies for extraterrestrial processing to the operational site. The emphasis has been on the use of near-term (pre-year 2000) propulsion systems, such as advanced chemical (H2, O2) and nuclear-electric systems. More exotic systems (mass drivers, nuclear-thermal rockets, etc.) were also considered to evaluate the potential to be gained by use of post-year 2000 technologies. Finally, the effects of using extraterrestrial propellants (e.g., H2 from lunar polar water-ice for chemical systems) were compared to those of propulsion systems deriving all or part of their propellants from the earth.

  16. Innovations in Mission Architectures for Human and Robotic Exploration Beyond Low Earth Orbit

    Science.gov (United States)

    Cooke, Douglas R.; Joosten, B. Kent; Lo, Martin W.; Ford, Ken; Hansen, Jack

    2002-01-01

    Through the application of advanced technologies, mission concepts, and new ideas in combining capabilities, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to discovery driven, technology enabled exploration. Numbers and masses of vehicles required are greatly reduced, yet enable the pursuit of a broader range of objectives. The scope of missions addressed range from the assembly and maintenance of arrays of telescopes for emplacement at the Earth-Sun L2, to Human missions to asteroids, the moon and Mars. Vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities; allowing for decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration.

  17. Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D., E-mail: gbeach@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2016-06-06

    We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

  18. Osculating Keplerian Elements for Highly Non-Keplerian Orbits

    Science.gov (United States)

    2017-03-27

    06 satellite and its orbital parameters are accurate with respect to the Yuma Almanac 2016* (week 0896, GPS Time of Applicability 405504 s). PRN-06...AFRL-AFOSR-UK-TR-2017-0026 Osculating Keplerian Elements for Highly Non-Keplerian Orbits Colin McInnes THE UNIVERSITY OF GLASGOW Final Report 03/27...Elements for Highly Non-Keplerian Orbits FINAL TECHNICAL REPORT Authors: Alessandro Peloni, Colin R. McInnes, Matteo Ceriotti Colin.McInnes

  19. Carbon Observations from Geostationary Earth Orbit as Part of an Integrated Observing System for Atmospheric Composition

    Science.gov (United States)

    Edwards, D. P.

    2015-12-01

    This presentation describes proposed satellite carbon measurements from the CHRONOS mission. The primary goal of this experiment is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. CHRONOS observations would provide measurements not currently available or planned as part of a surface, suborbital and satellite integrated observing system for atmospheric composition over North America. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution, and CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth

  20. Atomic Oxygen Erosion Yield Prediction for Spacecraft Polymers in Low Earth Orbit

    Science.gov (United States)

    Banks, Bruce A.; Backus, Jane A.; Manno, Michael V.; Waters, Deborah L.; Cameron, Kevin C.; deGroh, Kim K.

    2009-01-01

    The ability to predict the atomic oxygen erosion yield of polymers based on their chemistry and physical properties has been only partially successful because of a lack of reliable low Earth orbit (LEO) erosion yield data. Unfortunately, many of the early experiments did not utilize dehydrated mass loss measurements for erosion yield determination, and the resulting mass loss due to atomic oxygen exposure may have been compromised because samples were often not in consistent states of dehydration during the pre-flight and post-flight mass measurements. This is a particular problem for short duration mission exposures or low erosion yield materials. However, as a result of the retrieval of the Polymer Erosion and Contamination Experiment (PEACE) flown as part of the Materials International Space Station Experiment 2 (MISSE 2), the erosion yields of 38 polymers and pyrolytic graphite were accurately measured. The experiment was exposed to the LEO environment for 3.95 years from August 16, 2001 to July 30, 2005 and was successfully retrieved during a space walk on July 30, 2005 during Discovery s STS-114 Return to Flight mission. The 40 different materials tested (including Kapton H fluence witness samples) were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The MISSE 2 PEACE Polymers experiment used carefully dehydrated mass measurements, as well as accurate density measurements to obtain accurate erosion yield data for high-fluence (8.43 1021 atoms/sq cm). The resulting data was used to develop an erosion yield predictive tool with a correlation coefficient of 0.895 and uncertainty of +/-6.3 10(exp -25)cu cm/atom. The predictive tool utilizes the chemical structures and physical properties of polymers to predict in-space atomic oxygen erosion yields. A predictive tool concept (September 2009 version) is presented which represents an improvement over an earlier (December 2008) version.

  1. French Meteor Network for High Precision Orbits of Meteoroids

    Science.gov (United States)

    Atreya, P.; Vaubaillon, J.; Colas, F.; Bouley, S.; Gaillard, B.; Sauli, I.; Kwon, M. K.

    2011-01-01

    There is a lack of precise meteoroids orbit from video observations as most of the meteor stations use off-the-shelf CCD cameras. Few meteoroids orbit with precise semi-major axis are available using film photographic method. Precise orbits are necessary to compute the dust flux in the Earth s vicinity, and to estimate the ejection time of the meteoroids accurately by comparing them with the theoretical evolution model. We investigate the use of large CCD sensors to observe multi-station meteors and to compute precise orbit of these meteoroids. An ideal spatial and temporal resolution to get an accuracy to those similar of photographic plates are discussed. Various problems faced due to the use of large CCD, such as increasing the spatial and the temporal resolution at the same time and computational problems in finding the meteor position are illustrated.

  2. High-order-harmonic generation from field-distorted orbitals

    DEFF Research Database (Denmark)

    Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer

    2013-01-01

    We investigate the effect on high-order-harmonic generation of the distortion of molecular orbitals by the driving laser field. Calculations for high-order-harmonic generation including orbital distortion are performed for N2. Our results allow us to suggest that field distortion is the reason why...

  3. Low-earth-orbit Satellite Internet Protocol Communications Concept and Design

    Science.gov (United States)

    Slywezak, Richard A.

    2004-01-01

    This report presents a design concept for a low-Earth-orbit end-to-end Internet-Protocol- (IP-) based mission. The goal is to maintain an up-to-date communications infrastructure that makes communications seamless with the protocols used in terrestrial computing. It is based on the premise that the use of IPs will permit greater interoperability while also reducing costs and providing users the ability to retrieve data directly from the satellite. However, implementing an IP-based solution also has a number of challenges, since wireless communications have different characteristics than wired communications. This report outlines the design of a low-Earth-orbit end-to-end IP-based mission; the ideas and concepts of Space Internet architectures and networks are beyond the scope of this document. The findings of this report show that an IP-based mission is plausible and would provide benefits to the user community, but the outstanding issues must be resolved before a design can be implemented.

  4. Earth Observatory Satellite system definition study. Report no. 1: Orbit/launch vehicle tradeoff studies and recommendations

    Science.gov (United States)

    1974-01-01

    A study was conducted to determine the recommended orbit for the Earth Observatory Satellite (EOS) Land Resources Mission. It was determined that a promising sun synchronous orbit is 366 nautical miles when using an instrument with a 100 nautical mile swath width. The orbit has a 17 day repeat cycle and a 14 nautical mile swath overlap. Payloads were developed for each mission, EOS A through F. For each mission, the lowest cost booster that was capable of lifting the payload to the EOS orbit was selected. The launch vehicles selected for the missions are identified on the basis of tradeoff studies and recommendations. The reliability aspects of the launch vehicles are analyzed.

  5. End-of-life disposal of high elliptical orbit missions: The case of INTEGRAL

    Science.gov (United States)

    Armellin, Roberto; San-Juan, Juan F.; Lara, Martin

    2015-08-01

    Nowadays there is international consensus that space activities must be managed to minimize debris generation and risk. The paper presents a method for the end-of-life (EoL) disposal of spacecraft in high elliptical orbits (HEO). The time evolution of HEO is strongly affected by Earth's oblateness and luni-solar perturbation, and this can cause in the long-term to extended interferences with low Earth orbit (LEO) protected region and uncontrolled Earth re-entry. An EoL disposal concept that exploits the effect of orbital perturbations to reduce the disposal cost is presented. The problem is formulated as a multiobjective optimization problem, which is solved with an evolutionary algorithm. To explore at the best the search space a semi-analytical orbit propagator, which allows the propagation of the orbit motion for 100 years in few seconds, is adopted. The EoL disposal of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission is used as a practical test-case to show the effectiveness of the proposed methodology.

  6. A super-Earth orbiting the nearby M dwarf GJ 536

    Science.gov (United States)

    Suárez Mascareño, A.; González Hernández, J. I.; Rebolo, R.; Astudillo-Defru, N.; Bonfils, X.; Bouchy, F.; Delfosse, X.; Forveille, T.; Lovis, C.; Mayor, M.; Murgas, F.; Pepe, F.; Santos, N. C.; Udry, S.; Wünsche, A.; Velasco, S.

    2017-01-01

    We report the discovery of a super-Earth orbiting the star GJ 536 based on the analysis of the radial-velocity time series from the HARPS and HARPS-N spectrographs. GJ 536 b is a planet with a minimum mass Msini of 5.36 ± 0.69 M⊕; it has an orbital period of 8.7076 ± 0.0025 d at a distance of 0.066610(13) AU, and an orbit that is consistent with circular. The host star is the moderately quiet M1 V star GJ 536, located at 10 pc from the Sun. We find the presence of a second signal at 43 d that we relate to stellar rotation after analysing the time series of Ca II H&K and Hα spectroscopic indicators and photometric data from the ASAS archive. We find no evidence linking the short period signal to any activity proxy. We also tentatively derived a stellar magnetic cycle of less than 3 yr. The data used in this paper (Table A.1) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A108

  7. ARMA Prediction of SBAS Ephemeris and Clock Corrections for Low Earth Orbiting Satellites

    Directory of Open Access Journals (Sweden)

    Jeongrae Kim

    2015-01-01

    Full Text Available For low earth orbit (LEO satellite GPS receivers, space-based augmentation system (SBAS ephemeris/clock corrections can be applied to improve positioning accuracy in real time. The SBAS correction is only available within its service area, and the prediction of the SBAS corrections during the outage period can extend the coverage area. Two time series forecasting models, autoregressive moving average (ARMA and autoregressive (AR, are proposed to predict the corrections outside the service area. A simulated GPS satellite visibility condition is applied to the WAAS correction data, and the prediction accuracy degradation, along with the time, is investigated. Prediction results using the SBAS rate of change information are compared, and the ARMA method yields a better accuracy than the rate method. The error reductions of the ephemeris and clock by the ARMA method over the rate method are 37.8% and 38.5%, respectively. The AR method shows a slightly better orbit accuracy than the rate method, but its clock accuracy is even worse than the rate method. If the SBAS correction is sufficiently accurate comparing with the required ephemeris accuracy of a real-time navigation filter, then the predicted SBAS correction may improve orbit determination accuracy.

  8. Coupled thermo-orbital evolution of tidally-evolved Earth-like planets

    Science.gov (United States)

    Behounkova, Marie; Walterova, Michaela; Cadek, Ondrej; Tobie, Gabriel; Choblet, Gael

    2016-10-01

    Progress in detection techniques of exoplanets inspired increasing number of studies focused on their internal dynamics and evolution. The detection methods tend to favor the discovery of short-period exoplanets, that are predicted to get rapidly tidally locked. During the locking process planets despin and a significant amount of tidal heating may contribute to the thermal budget of the planet. Moreover, tidally locked exoplanets exhibit large surface temperature contrasts between sub-stellar and anti-stellar sides due to uneven insolation which influence the convection pattern and cooling of the planet. Here, we will present the evolution of tidally locked Earth-like exoplanets using numerical tool Antigone (Behounkova et al., 2010, 2011) coupling long-term internal evolution, tidal dissipation (taking into account Maxwell or Andrade rheology) and uneven insolation pattern. For constant orbital parameters, we will focus on numerical simulation of the heat transfer in exoEarths for various rheological properties of planet and various values of spin-orbit resonance, semi-major axis, eccentricity and luminosity of star. In the case of effective heat transfer, our results suggest that the melting is mainly observed within the upper part of the mantle for tidal heating lower than 100TW . For tidal heating higher than 100TW, the melt is produced also within the deep part of the mantle and degree-2 convection is enhanced due to tidal heating pattern. For large tidal heating (larger than 1000TW), global melting is observed and temperature field is homogenized due to global melting, the heat transfer is mainly due to melt extraction and advection is suppressed. We will further present first results of coupled orbital-internal evolution of planets without companion using numerical model of orbital evolution with realistic (Maxwell or Andrade) rheology (Walterova et al., in prep). We will concentrate on the capture into the spin-orbit resonance. Special attention will be

  9. Design and "As Flown" Radiation Environments for Materials in Low Earth Orbit

    Science.gov (United States)

    Minow, Joseph; McWilliams, Brett; Altstatt, Richard; Koontz, Steven

    2006-01-01

    A conservative design approach was adopted by the International Space Station Program for specifying total ionizing radiation dose requirements for use in selecting and qualifying materials for construction of the International Space Station. The total ionizing dose design environment included in SSP 30512 Space Station Ionizing Radiation Design Environment is based on trapped proton and electron fluence derived from the solar maximum versions of the AE-8 and AP-8 models, respectively, specified for a circular orbit at 500 km altitude and 51.7 degree inclination. Since launch, the range of altitudes utilized for Space Station operations vary from a minimum of approximately 330 km to a maximum of approximately 405 km with a mean operational altitude less than 400 km. The design environment, therefore, overestimates the radiation environment because the particle flux in the South Atlantic Anomaly is the primary contributor to radiation dose in low Earth orbit and flux within the Anomaly is altitude dependent. In addition, a 2X multiplier is often applied to the design environment to cover effects from the contributions of galactic cosmic rays, solar energetic particle events, geomagnetic storms, and uncertainties in the trapped radiation models which are not explicitly included in the design environment. Application of this environment may give radiation dose overestimates on the order of 1OX to 30X for materials exposed to the space environment, suggesting that materials originally qualified for ten year exposures on orbit may be used for longer periods without replacement. In this paper we evaluate the "as flown" radiation environments derived from historical records of the ISS flight trajectory since launch and compare the results with the SSP 30512 design environment to document the magnitude of the radiation dose overestimate provided by the design environment. "As flown" environments are obtained from application of the AE-8/AP-8 trapped particle models along

  10. Assessment of the consequences of the Fengyun-1C breakup in low Earth orbit

    Science.gov (United States)

    Pardini, Carmen

    On 11 January 2007, the 880 kg (958 kg at launch) weather spacecraft Fengyun-1C, launched on 10 May 1999 into a sun-synchronous orbit with a CZ-4B booster from the Taiyuan Satellite Launch Center, was destroyed over central China as a result of the first successful Chinese anti-satellite weapon test. It was carried out with a direct ascent interception with a kinetic energy kill vehicle launched by an SC-19 missile, fired from a mobile ground platform close to the Xichang Satellite Launch Center. While the technical details of the test, probably the third attempt, and the characteristics of the weapon used remain shrouded in secrecy, the intentional breakup of the aging weather spacecraft, fully functional until 2005, produced a huge amount of debris in one of the orbital regimes already most affected by past fragmentation events. At present, the US Space Surveillance Network has identified about 2600 objects, typically larger than 10 cm, but the fragments larger than 1 cm may be more than 100,000. After two decades of substantial international progress in the field of orbital debris mitigation, in order to preserve the low Earth and geosynchronous environments for future space missions, the Fengyun-1C destruction represented a serious turnabout. In fact, it abruptly increased by approximately 20% the number of cataloged debris in orbit. To give a rough idea of the impact of this single event on the circumterrestrial environment, it is sufficient to realize that about 15 years of global space activity - including failures and accidental breakups - had been needed to increase, by a comparable amount, the number of cataloged debris in orbit to the level observed before the Chinese anti-satellite test. The purpose of this presentation is to assess the impact of the debris cloud generated by the Fengyun-1C breakup on the low Earth environment. The anti-satellite test was carried out at an altitude of about 863 km, spreading the cataloged fragments between 200 and 4000

  11. Orbits

    CERN Document Server

    Xu, Guochang

    2008-01-01

    This is the first book of the satellite era which describes orbit theory with analytical solutions of the second order with respect to all possible disturbances. Based on such theory, the algorithms of orbits determination are completely revolutionized.

  12. Cost-effective and robust mitigation of space debris in low earth orbit

    Science.gov (United States)

    Walker, R.; Martin, C.

    It is predicted that the space debris population in low Earth orbit (LEO) will continue to grow and in an exponential manner in the long-term due to an increasing rate of collisions between large objects, unless internationally-accepted space debris mitigation measures are adopted soon. Such measures are aimed at avoiding the future generation of space debris objects and primarily need to be effective in preventing significant long-term growth in the debris population, even in the potential scenario of an increase in future space activity. It is also important that mitigation measures can limit future debris population levels, and therefore the underlying collision risk to space missions, to the lowest extent possible. However, for their wide acceptance, the cost of implementation associated with mitigation measures needs to be minimised as far as possible. Generally, a lower collision risk will cost more to achieve and vice versa, so it is necessary to strike a balance between cost and risk in order to find a cost-effective set of mitigation measures. In this paper, clear criteria are established in order to assess the cost-effectiveness of space debris mitigation measures. A full cost-risk-benefit trade-off analysis of numerous mitigation scenarios is presented. These scenarios consider explosion prevention and post-mission disposal of space systems, including de-orbiting to limited lifetime orbits and re-orbiting above the LEO region. The ESA DELTA model is used to provide long-term debris environment projections for these scenarios as input to the benefit and risk parts of the trade-off analysis. Manoeuvre requirements for the different post-mission disposal scenarios were also calculated in order to define the cost-related element. A 25-year post-mission lifetime de-orbit policy, combined with explosion prevention and mission-related object limitation, was found to be the most cost-effective solution to the space debris problem in LEO. This package would also

  13. Analytic model for the long-term evolution of circular Earth satellite orbits including lunar node regression

    Science.gov (United States)

    Zhu, Ting-Lei; Zhao, Chang-Yin; Zhang, Ming-Jiang

    2017-04-01

    This paper aims to obtain an analytic approximation to the evolution of circular orbits governed by the Earth's J2 and the luni-solar gravitational perturbations. Assuming that the lunar orbital plane coincides with the ecliptic plane, Allan and Cook (Proc. R. Soc. A, Math. Phys. Eng. Sci. 280(1380):97, 1964) derived an analytic solution to the orbital plane evolution of circular orbits. Using their result as an intermediate solution, we establish an approximate analytic model with lunar orbital inclination and its node regression be taken into account. Finally, an approximate analytic expression is derived, which is accurate compared to the numerical results except for the resonant cases when the period of the reference orbit approximately equals the integer multiples (especially 1 or 2 times) of lunar node regression period.

  14. Investigation of Teflon FEP Embrittlement on Spacecraft in Low Earth Orbit

    Science.gov (United States)

    deGroh, Kim K.; Smith, Daniela C.

    1997-01-01

    Teflon(registered trademark) FEP (fluorinated ethylene-propylene) is commonly used on exterior spacecraft surfaces in the low Earth orbit (LEO) environment for thermal control. Silverized or aluminized FEP is used for the outer layer of thermal control blankets because of its low solar absorptance and high thermal emittance. FEP is also preferred over other spacecraft polymers because of its relatively high resistance to atomic oxygen erosion. Because of its low atomic oxygen erosion yield, FEP has not been protected in the space environment. Recent, long term space exposures such as on the Long Duration Exposure Facility (LDEF, 5.8 years in space), and the Hubble Space Telescope (HST, after 3.6 years in space) have provided evidence of LEO environmental degradation of FEP. These exposures provide unique opportunities for studying environmental degradation because of the long durations and the different conditions (such as differences in altitude) of the exposures. Samples of FEP from LDEF and from HST (retrieved during its first servicing mission) have been evaluated for solar induced embrittlement and for synergistic effects of solar degradation and atomic oxygen. Micro-indenter results indicate that the surface hardness increased as the ratio of atomic oxygen fluence to solar fluence decreased for the LDEF samples. FEP multilayer insulation (MLI) retrieved from HST provided evidence of severe embrittlement on solar facing surfaces. Micro-indenter measurements indicated higher surface hardness values for these samples than LDEF samples, but the solar exposures were higher. Cracks induced during bend testing were significantly deeper for the HST samples with the highest solar exposure than for LDEF samples with similar atomic oxygen fluence to solar fluence ratios. If solar fluences are compared, the LDEF samples appear as damaged as HST samples, except that HST had deeper induced cracks. The results illustrate difficulties in comparing LEO exposed materials from

  15. Frozen orbits for satellites close to an earth-like planet

    Science.gov (United States)

    Coffey, Shannon L.; Deprit, Andre; Deprit, Etienne

    1994-05-01

    We say that a planet is Earth-like if the coefficient of the second order zonal harmonic dominates all other coefficients in the gravity field. This paper concerns the zonal problem for satellites around an Earth-like planet, all other perturbations excluded. The potential contains all zonal coefficients J2 through J9. The model problem is averaged over the mean anomaly by a Lie transformation to the second order; we produce the resulting Hamiltonian as a Fourier series in the argument of perigee whose coefficients are algebraic functions of the eccentricity - not truncated power series. We then proceed to a global exploration of the equilibria in the averaged problem. These singularities which aerospace engineers know by the name of frozen orbits are located by solving the equilibria equations in two ways, (1) analytically in the neighborhood of either the zero eccentricity or the critical inclination, and (2) numerically by a Newton-Raphson iteration applied to an approximate position read from the color map of the phase flow. The analytical solutions we supply in full to assist space engineers in designing survey missions. We pay special attention to the manner in which additional zonal coefficients affect the evolution of bifurcations we had traced earlier in the main problem (J2 only). In particular, we examine the manner in which the odd zonal J3 breaks the discrete symmetry inherent to the even zonal problem. In the even case, we find that Vinti's problem (J4 + J22 = 0) p resents a degeneracy in the form of non-isolated equilibria; we surmise that the degeneracy is a reflection of the fact that Vinti's problem is separable. By numerical continuation we have discovered three families of frozen orbits in the full zonal problem under consideration; (1) a family of stable equilibria starting from the equatorial plane and tending to the critical inclination; (2) an unstable family arising from the bifurcation at the critical inclination; (3) a stable family also

  16. Applying KAM Theory to Highly Eccentric Orbits

    Science.gov (United States)

    2014-03-27

    period of a planet is proportional to the cube of the semi- major axis of its orbit. In 1687, Isaac Newton would prove Kepler’s discoveries after...solving the n-body problem) gave way for more exhaustive research efforts of Newton , Euler, Lagrange, Jacobi, Poincaré, and many others. The King...coordinates, H(I, θ) = H ′(I′), (2.5) 3. Solving the Hamilton-Jacobi equation for the following generating function (Equa- tion (2.6) using a Newton

  17. Stellar orbits in the Galaxy and mass extinctions on the Earth: a connection?

    Science.gov (United States)

    Porto de Mello, G. F.; Dias, W. S.; Lepine, J.; Lorenzo-Oliveira, D.; Kazu, R. S.

    2014-03-01

    The orbits of the stars in the disk of the Galaxy, and their passages through the Galactic spiral arms, are a rarely mentioned factor of biosphere stability which might be important for long-term planetary climate evolution, with a possible bearing on mass extinctions. The Sun lies very near the co-rotation radius, where stars revolve around the Galaxy in the same period as the density wave perturbations of the spiral arms (Dias & Lepine 2005). Conventional wisdom generally considers that this status makes for few passages through the spiral arms. Controversy still surrounds whether time spent inside or around spiral arms is dangerous to biospheres and conducive to mass extinctions (Bailer-Jones 2009). Possible threats include giant molecular clouds disturbing the Oort comet cloud and provoking heavy bombardment (Clube & Napier 1982); a higher exposure to cosmic rays near star forming regions triggering increased cloudiness in Earth's atmosphere and ice ages (Gies & Helsel 2005); and the destruction of Earth's ozone layer posed by supernova explosions (Gehrels et al 2003). We present detailed calculations of the history of spiral arm passages for all 212 solartype stars nearer than 20 parsecs, including the total time spent inside the spiral arms in the last 500 million years, when the spiral arm position can be traced with good accuracy. There is a very large diversity of stellar orbits amongst solar neighborhood solar-type stars, and the time fraction spent inside spiral arms can vary from a few percent to nearly half the time. The Sun, despite its proximity to the galactic co-rotation radius, has exceptionally low eccentricity and a low vertical velocity component, and therefore spends 40% of its lifetime crossing the spiral arms, more than nearly all nearby stars. We discuss the possible implications of this fact to the long-term habitability of the Earth, and possible correlations of the Sun's passage through the spiral arms with the five great mass

  18. Designing high-Performance layered thermoelectric materials through orbital engineering

    DEFF Research Database (Denmark)

    Zhang, Jiawei; Song, Lirong; Madsen, Georg K. H.

    2016-01-01

    Thermoelectric technology, which possesses potential application in recycling industrial waste heat as energy, calls for novel high-performance materials. The systematic exploration of novel thermoelectric materials with excellent electronic transport properties is severely hindered by limited...... insight into the underlying bonding orbitals of atomic structures. Here we propose a simple yet successful strategy to discover and design high-performance layered thermoelectric materials through minimizing the crystal field splitting energy of orbitals to realize high orbital degeneracy. The approach......-abundant elements. Moreover, the approach can be extended to several other non-cubic materials, thereby substantially accelerating the screening and design of new thermoelectric materials....

  19. Cost-effective technology advancement directions for electric propulsion transportation systems in earth-orbital missions

    Science.gov (United States)

    Regetz, J. D., Jr.; Terwilliger, C. H., Jr.

    1979-01-01

    This paper presents the results of a study to determine the directions that electric propulsion technology should take to meet the primary propulsion requirements for earth-orbital missions of the next three decades in the most cost-effective manner. Discussed are the mission set requirements, state-of-the-art electric propulsion technology and the baseline system characterized by it, adequacy of the baseline system to meet the mission set requirements, cost-optimum electric propulsion system characteristics for the mission set, and sensitivities of mission costs and design points to system-level electric propulsion parameters. It is found that the efficiency-specific impulse characteristic generally has a more significant impact on overall costs than specific masses or costs of propulsion and power systems.

  20. Changes in the Optical Properties of Materials Are Observed After 18 Months in Low Earth Orbit

    Science.gov (United States)

    Jaworske, Donald A.

    1999-01-01

    Materials located on the exterior of spacecraft in low Earth orbit are subjected to a number of environmental threats, including atomic oxygen, ultraviolet radiation, thermal cycling, and micrometeroid and debris impact. Atomic oxygen attacks materials vulnerable to oxidation. Ultraviolet radiation can break chemical bonds and cause undesirable changes in optical properties. Thermal cycling can cause cracking, and micrometeroid and debris impacts can damage protective coatings. Another threat is contamination. The outgassing of volatile chemicals can contaminate nearby surfaces, changing their thermal control properties. Contaminated surfaces may undergo further change as a result of atomic oxygen and ultraviolet radiation exposure. The Passive Optical Sample Assembly (POSA) experiment was designed as a risk mitigation experiment for the International Space Station. Samples were characterized before launch, exposed for 18 months on the exterior of Mir, and characterized upon their return. Lessons learned from POSA about the durability of material properties can be applied to the space station and other long-duration missions.

  1. Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

    Science.gov (United States)

    Carter, P.; Beach, M. A.

    1993-01-01

    This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

  2. Orbital

    OpenAIRE

    Yourshaw, Matthew Stephen

    2017-01-01

    Orbital is a virtual reality gaming experience designed to explore the use of traditional narrative structure to enhance immersion in virtual reality. The story structure of Orbital was developed based on the developmental steps of 'The Hero's Journey,' a narrative pattern identified by Joseph Campbell. Using this standard narrative pattern, Orbital is capable of immersing the player quickly and completely for the entirety of play time. MFA

  3. International Space Station as a base camp for exploration beyond low Earth orbit

    Science.gov (United States)

    Raftery, Michael; Hoffman, Jeffrey

    2013-04-01

    The idea for using the International Space Station (ISS) as a platform for exploration has matured in the past few years and the concept continues to gain momentum. ISS provides a robust infrastructure which can be used to test systems and capabilities needed for missions to the Moon, Mars, asteroids and other potential destinations. International cooperation is a critical enabler and ISS has already demonstrated successful management of a large multi-national technical endeavor. Systems and resources needed for expeditions can be aggregated and thoroughly tested at ISS before departure thus providing wide operational flexibility and the best assurance of mission success. A small part of ISS called an Exploration Platform (ISS-EP) can be placed in cislunar space providing immediate benefits and flexibility for future exploration missions. We will show how ISS and the ISS-EP can be used to reduce risk and improve the operational flexibility for missions beyond low Earth orbit. Life support systems and other technologies developed for ISS can be evolved and adapted to the ISS-EP and other exploration spacecrafts. New technology, such as electric propulsion and advanced life support systems can be tested and proven at ISS as part of an incremental development program. Commercial companies who are introducing transportation and other services will benefit with opportunities to contribute to the mission since ISS will serve as a focal point for the commercialization of low earth orbit services. Finally, we will show how the use of ISS provides immediate benefits to the scientific community because its capabilities are available today and certain critical aspects of exploration missions can be simulated.

  4. Viscoelastic characterization of thin-film polymers exposed to low Earth orbit

    Science.gov (United States)

    Letton, Alan; Farrow, Allan; Strganac, Thomas

    1993-01-01

    The materials made available through the Long Duration Exposure Facility (LDEF) satellite provide a set of specimens that can be well characterized and have a known exposure history with reference to atomic oxygen and ultraviolet radiation exposure. Mechanical characteristics measured from control samples and exposed samples provide a data base for predicting the behavior of polymers in low earth orbit. Samples of 1.0 mil thick low density polyethylene were exposed to the low earth orbit environment for a period of six years. These materials were not directly exposed to ram atomic oxygen and offer a unique opportunity for measuring the effect of atomic oxygen and UV radiation on mechanical properties with little concern to the effect of erosion. The viscoelastic characteristics of these materials were measured and compared to the viscoelastic characteristics of control samples. To aid in differentiating the effects of changes in crystallinity resulting from thermal cycling, from the effects of changes in chemical structure resulting from atomic oxygen/UV attack to the polymer, a second set of control specimens, annealed to increase crystallinity, were measured as well. The resulting characterization of these materials will offer insight into the impact of atomic oxygen/UV on the mechanical properties of polymeric materials. The viscoelastic properties measured for the control, annealed, and exposed specimens were the storage and loss modulus as a function of frequency and temperature. From these datum is calculated the viscoelastic master curve derived using the principle of time/temperature superposition. Using the master curve, the relaxation modulus is calculated using the method of Ninomiya and Ferry. The viscoelastic master curve and the stress relaxation modulus provide a direct measure of the changes in the chemical or morphological structure. In addition, the effect of these changes on long-term and short-term mechanical properties is known directly. It

  5. Analysis of Approaches to the Near-Earth Orbit Cleanup from Space Debris of the Size Below10 cm

    Directory of Open Access Journals (Sweden)

    V. I. Maiorova

    2016-01-01

    Full Text Available Nowadays, there are a lot of concepts aimed at space debris removal from the near-Earth orbits being under way at different stages of detailed engineering and design. As opposed to large-size space debris (upper-stages, rocket bodies, non-active satellites, to track the small objects of space debris (SOSD, such as picosatellites, satellite fragments, pyrotechnic devices, and other items less than 10 cm in size, using the ground stations is, presently, a challenge.This SOSD feature allows the authors to propose the two most rational approaches, which use, respectively, a passive and an active (prompt maneuverable space vehicles (SV and appropriate schematic diagrams for their collection:1 Passive scheme – space vehicle (SV to be launched into an orbit is characterized by high mathematical expectation of collision with a large amount of SOSD and, accordingly, by high probability to be captured using both active or the passive tools. The SV does not execute any maneuvers, but can be equipped with a propulsion system required for orbit’s maintenance and correction and also for solving the tasks of long-range guidance.2 Active scheme – the SV is to be launched into the target or operating orbit and executes a number of maneuvers to capture the SOSD using both active and passive tools. Thus, such a SV has to be equipped with a rather high-trust propulsion system, which allows the change of its trajectory and also with the guidance system to provide it with target coordinates. The guidance system can be built on either radio or optical devices, it can be installed onboard the debris-removal SV or onboard the SV which operates as a supply unit (if such SVs are foreseen.The paper describes each approach, emphasizes advantages and disadvantages, and defines the cutting-edge technologies to be implemented.

  6. Analysis of Static Spacecraft Floating Potential at Low Earth Orbit (LEO)

    Science.gov (United States)

    Herr, Joel L.; Hwang, K. S.; Wu, S. T.

    1995-01-01

    Spacecraft floating potential is the charge on the external surfaces of orbiting spacecraft relative to the space. Charging is caused by unequal negative and positive currents to spacecraft surfaces. The charging process continues until the accelerated particles can be collected rapidly enough to balance the currents at which point the spacecraft has reached its equilibrium or floating potential. In low inclination. Low Earth Orbit (LEO), the collection of positive ion and negative electrons. in a particular direction. are typically not equal. The level of charging required for equilibrium to be established is influenced by the characteristics of the ambient plasma environment. by the spacecraft motion, and by the geometry of the spacecraft. Using the kinetic theory, a statistical approach for studying the interaction is developed. The approach used to study the spacecraft floating potential depends on which phenomena are being applied. and on the properties of the plasma. especially the density and temperature. The results from kinetic theory derivation are applied to determine the charging level and the electric potential distribution at an infinite flat plate perpendicular to a streaming plasma using finite-difference scheme.

  7. Essentials for Team Based Rehearsals and the Differences Between Earth Orbiting and Deep Space Missions

    Science.gov (United States)

    Gomez-Rosa, Carlos; Cifuentes, Juan; Wasiak, Francis; Alfonzo, Agustin

    2015-01-01

    The mission readiness environment is where spacecraft and ground systems converge to form the entire as built flight system for the final phase of operationally-themed testing. For most space missions, this phase starts between nine to twelve months prior to the planned launch. In the mission readiness environment, the goal is to perform sufficient testing to exercise the flight teams and systems through all mission phases in order to demonstrate that all elements are ready to support. As part of the maturation process, a mission rehearsal program is introduced to focus on team processes within the final flight system, in a more realistic operational environment. The overall goal for a mission rehearsal program is to: 1) ensure all flight system elements are able to meet mission objectives as a cohesive team; 2) reduce the risk in space based operations due to deficiencies in people, processes, procedures, or systems; and 3) instill confidence in the teams that will execute these first time flight activities. A good rehearsal program ensures critical events are exercised, discovers team or flight system nuances whose impact were previously unknown, and provides a real-time environment in which to interact with the various teams and systems. For flight team members, the rehearsal program provides experience and training in the event of planned (or unplanned) flight contingencies. To preserve the essence for team based rehearsals, this paper will explore the important elements necessary for a successful rehearsal program, document differences driven by Earth Orbiting (Aqua, Aura, Suomi-National Polar-orbiting Partnership (NPP)) and Deep Space missions (New Horizons, Mars Atmosphere and Volatile EvolutioN (MAVEN)) and discuss common challenges to both mission types. In addition, large scale program considerations and enhancements or additional steps for developing a rehearsal program will also be considered. For NASA missions, the mission rehearsal phase is a key

  8. [Orbital vasculonervous network and orbital surgical compartments by high field magnetic resonance].

    Science.gov (United States)

    Hernández González, L C; Suárez Suárez, E; Dos Santos Bernardo, V; Junceda Moreno, J; Recio Rodríguez, M; Martínez De Vega, V; Viaño López, J

    2003-10-01

    To elucidate the possibilities and indications of high-resolution magnetic resonance imaging (MRI) in the study of the orbit and its contents. Orbital anatomy was studied in sliced specimens of fifteen fresh frozen cadavers and the results were compared with those obtained in thirty asymptomatic subjects who underwent a magnetic resonance with 1.5 Tesla equipment. The information obtained was used to interpret the findings in twenty-two patients with various orbital diseases. High-resolution MRI allows visualization of structures difficult to assess previously, like the cerebrospinal fluid (CSF) surrounding the optic nerve, the complete intraorbital route and the exit of the third cranial nerve, the ophthalmic artery and the intraorbital relationships of the sixth cranial nerve, which can be clearly differentiated from the lateral rectus muscle. High-resolution MRI is a very useful tool for the study of the orbit and its content. It provides accurate diagnoses through non-invasive procedures and facilitates the planning of the surgical approaches by improving the visualization of pathologic orbital structures. lcarlos@correo.uniovi.es

  9. Geosynchronous inclined orbits for high-latitude communications

    Science.gov (United States)

    Fantino, E.; Flores, R. M.; Di Carlo, M.; Di Salvo, A.; Cabot, E.

    2017-11-01

    We present and discuss a solution to the growing demand for satellite telecommunication coverage in the high-latitude geographical regions (beyond 55°N), where the signal from geostationary satellites is limited or unavailable. We focus on the dynamical issues associated to the design, the coverage, the maintenance and the disposal of a set of orbits selected for the purpose. Specifically, we identify a group of highly inclined, moderately eccentric geosynchronous orbits derived from the Tundra orbit (geosynchronous, eccentric and critically inclined). Continuous coverage can be guaranteed by a constellation of three satellites in equally spaced planes and suitably phased. By means of a high-precision model of the terrestrial gravity field and the relevant environmental perturbations, we study the evolution of these orbits. The effects of the different perturbations on the ground track (which is more important for coverage than the orbital elements themselves) are isolated and analyzed. The physical model and the numerical setup are optimized with respect to computing time and accuracy. We show that, in order to maintain the ground track unchanged, the key parameters are the orbital period and the argument of perigee. Furthermore, corrections to the right ascension of the ascending node are needed in order to preserve the relative orientation of the orbital planes. A station-keeping strategy that minimizes propellant consumption is then devised, and comparisons are made between the cost of a solution based on impulsive maneuvers and one with continuous thrust. Finally, the issue of end-of-life disposal is discussed.

  10. Advantage of Animal Models with Metabolic Flexibility for Space Research Beyond Low Earth Orbit

    Science.gov (United States)

    Griko, Yuri V.; Rask, Jon C.; Raychev, Raycho

    2017-01-01

    As the world's space agencies and commercial entities continue to expand beyond Low Earth Orbit (LEO), novel approaches to carry out biomedical experiments with animals are required to address the challenge of adaptation to space flight and new planetary environments. The extended time and distance of space travel along with reduced involvement of Earth-based mission support increases the cumulative impact of the risks encountered in space. To respond to these challenges, it becomes increasingly important to develop the capability to manage an organism's self-regulatory control system, which would enable survival in extraterrestrial environments. To significantly reduce the risk to animals on future long duration space missions, we propose the use of metabolically flexible animal models as "pathfinders," which are capable of tolerating the environmental extremes exhibited in spaceflight, including altered gravity, exposure to space radiation, chemically reactive planetary environments and temperature extremes. In this report we survey several of the pivotal metabolic flexibility studies and discuss the importance of utilizing animal models with metabolic flexibility with particular attention given to the ability to suppress the organism's metabolism in spaceflight experiments beyond LEO. The presented analysis demonstrates the adjuvant benefits of these factors to minimize damage caused by exposure to spaceflight and extreme planetary environments. Examples of microorganisms and animal models with dormancy capabilities suitable for space research are considered in the context of their survivability under hostile or deadly environments outside of Earth. Potential steps toward implementation of metabolic control technology in spaceflight architecture and its benefits for animal experiments and manned space exploration missions are discussed.

  11. Validation of the new trapped environment AE9/AP9/SPM at low Earth orbit

    Science.gov (United States)

    Badavi, Francis F.

    2014-09-01

    The completion of the international space station (ISS) in 2011 has provided the space research community an ideal proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the validation of radiation environmental models, nuclear transport codes and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) provided vital information impacting both the environmental models and the nuclear transport code developments by indicating the need for an improved dynamic model of the low Earth orbit (LEO) trapped environment. Additional studies using thermo-luminescent detector (TLD), tissue equivalent proportional counter (TEPC) area monitors, and computer aided design (CAD) model of earlier ISS configurations, confirmed STS observations that, as input, computational dosimetry requires an environmental model with dynamic and directional (anisotropic) behavior, as well as an accurate six degree of freedom (DOF) definition of the vehicle attitude and orientation along the orbit of ISS. At LEO, a vehicle encounters exposure from trapped particles and attenuated galactic cosmic rays (GCR). Within the trapped field, a challenge arises from properly estimating the amount of exposure acquired. There exist a number of models to define the intensities of the trapped particles during the solar quiet and active times. At active times, solar energetic particles (SEP) generated by solar flare or coronal mass ejection (CME) also contribute to the exposure at high northern and southern latitudes. Among the more established trapped models are the historic and popular AE8/AP8, dating back to the 1980s, the historic and less popular CRRES electron/proton, dating back to 1990s and the recently released AE9/AP9/SPM. The AE9/AP9/SPM model is a major improvement over the older AE8/AP8 and CRRES models. This model is derived from numerous measurements acquired over four

  12. Detection, identification, and classification of mosquito larval habitats using remote sensing scanners in earth-orbiting satellites*

    Science.gov (United States)

    Hayes, Richard O.; Maxwell, Eugene L.; Mitchell, Carl J.; Woodzick, Thomas L.

    1985-01-01

    A method of identifying mosquito larval habitats associated with fresh-water plant communities, wetlands, and other aquatic locations at Lewis and Clark Lake in the states of Nebraska and South Dakota, USA, using remote sensing imagery obtained by multispectral scanners aboard earth-orbiting satellites (Landsat 1 and 2) is described. The advantages and limitations of this method are discussed. PMID:2861917

  13. Preliminary investigations on a NTP cargo shuttle for earth to moon orbit payload transfer based on a particle bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Raepsaet, X.; Proust, E.; Gervaise, F.; Baraer, L.; Naury, S.; Linet, F.L. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Mecanique et de Technologie; Bresson, C.F.; Coriolis, C.C. de; Bergeron, I.T.A.; Bourquin, L.V.; Clech, L.V.; Devaux, L.V.; Chevillot, L.V.; Augier, E.V. [EAMEA, 50 - Cherbourg (France)

    1995-12-01

    MAPS, a 3-year study program on NTP has recently been launched at CEA following the conclusions of a preliminary scoping study of an NTP system for earth to moon orbit cargo shuttle missions. This paper presents the main results of this scoping study, and gives an outline of the MAPS program. (authors). 5 figs., 11 tabs., 7 refs.

  14. Orbit Control of Fly-around Satellite with Highly Eccentric Orbit Using Solar Radiation Pressure

    Science.gov (United States)

    Yong-gang, Hou; Chang-yin, Zhao; Ming-jiang, Zhang; Rong-yu, Sun

    2017-01-01

    The method of controlling highly eccentric accompanying flight orbit using the solar wing is proposed in this paper. The formation is maintained by controlling the orbit of the accompanying satellite (follower). The accompanying satellite rotates around its inertial principal axis with a constant angular velocity. The control on the accompanying satellite is divided into the in-plane control and out-of-plane control. The in-plane control is superior to the out-of-plane control. The out-of-plane control force is applied when the in-plane error is eliminated or the in-plane control force can not be supplied due to some geometrical factors. By the sliding mode control method, the magnitude and direction of the control force required by the in-plane orbit control are calculated. Then accordingly, the expression of the solar wing orientation with respect to the satellite body in the control process is derived, so that by adjusting the orientation of the solar wing, the required control force can be obtained. Finally, the verification on this method is performed by numerical simulations, including the orbit adjustment, error elimination, and the orbit maintenance. It is shown that this method can keep the error less than 5 m, and it is feasible for the space formation flight.

  15. Detection of Earth-rotation Doppler shift from Suomi National Polar-Orbiting Partnership Cross-Track Infrared Sounder.

    Science.gov (United States)

    Chen, Yong; Han, Yong; Weng, Fuzhong

    2013-09-01

    The Cross-Track Infrared Sounder (CrIS) on the Suomi National Polar-Orbiting Partnership Satellite is a Fourier transform spectrometer and provides a total of 1305 channels for sounding the atmosphere. Quantifying the CrIS spectral accuracy, which is directly related to radiometric accuracy, is crucial for improving its data assimilation in numerical weather prediction. In this study, a cross-correlation method is used for detecting the effect of Earth-rotation Doppler shift (ERDS) on CrIS observations. Based on a theoretical calculation, the ERDS can be as large as about 1.3 parts in 10(6) (ppm) near Earth's equator and at the satellite scan edge for a field of regard (FOR) of 1 or 30. The CrIS observations exhibit a relative Doppler shift as large as 2.6 ppm for a FOR pair of 1 and 30 near the equator. The variation of the ERDS with latitude and scan position detected from CrIS observations is similar to that derived theoretically, which indicates that the spectral stability of the CrIS instrument is very high. To accurately calibrate CrIS spectral accuracy, the ERDS effect should be removed. Since the ERDS is easily predictable, the Doppler shift is correctable in the CrIS spectra.

  16. High Performance Database Management for Earth Sciences

    Science.gov (United States)

    Rishe, Naphtali; Barton, David; Urban, Frank; Chekmasov, Maxim; Martinez, Maria; Alvarez, Elms; Gutierrez, Martha; Pardo, Philippe

    1998-01-01

    The High Performance Database Research Center at Florida International University is completing the development of a highly parallel database system based on the semantic/object-oriented approach. This system provides exceptional usability and flexibility. It allows shorter application design and programming cycles and gives the user control via an intuitive information structure. It empowers the end-user to pose complex ad hoc decision support queries. Superior efficiency is provided through a high level of optimization, which is transparent to the user. Manifold reduction in storage size is allowed for many applications. This system allows for operability via internet browsers. The system will be used for the NASA Applications Center program to store remote sensing data, as well as for Earth Science applications.

  17. The High Definition Earth Viewing (HDEV) Payload

    Science.gov (United States)

    Muri, Paul; Runco, Susan; Fontanot, Carlos; Getteau, Chris

    2017-01-01

    The High Definition Earth Viewing (HDEV) payload enables long-term experimentation of four, commercial-of-the-shelf (COTS) high definition video, cameras mounted on the exterior of the International Space Station. The payload enables testing of cameras in the space environment. The HDEV cameras transmit imagery continuously to an encoder that then sends the video signal via Ethernet through the space station for downlink. The encoder, cameras, and other electronics are enclosed in a box pressurized to approximately one atmosphere, containing dry nitrogen, to provide a level of protection to the electronics from the space environment. The encoded video format supports streaming live video of Earth for viewing online. Camera sensor types include charge-coupled device and complementary metal-oxide semiconductor. Received imagery data is analyzed on the ground to evaluate camera sensor performance. Since payload deployment, minimal degradation to imagery quality has been observed. The HDEV payload continues to operate by live streaming and analyzing imagery. Results from the experiment reduce risk in the selection of cameras that could be considered for future use on the International Space Station and other spacecraft. This paper discusses the payload development, end-to- end architecture, experiment operation, resulting image analysis, and future work.

  18. The Characterization of Non-Gravitational Perturbations That Act on Near-Earth Asteroid Orbits

    Science.gov (United States)

    Margot, Jean-Luc; Greenberg, Adam H.; Verma, Ashok K.; Taylor, Patrick A.

    2017-10-01

    The Yarkovsky effect is a thermal process acting upon the orbits of small celestial bodies which can cause these orbits to slowly expand or contract with time. The effect is subtle -- typical drift rates lie near 1e-4 au/My for a ~1 km diameter object -- and is thus generally difficult to measure. However, objects with long observation intervals, as well as objects with radar detections, serve as excellent candidates for the observation of this effect.We analyzed both optical and radar astrometry for all numbered Near-Earth Asteroids (NEAs), as well as several un-numbered NEAs. In order to quantify the likelihood of Yarkovsky detections, we developed a metric based on the quality of Yarkovsky fits as compared to that of gravity-only fits. Based on the metric results, we report 167 objects with measured Yarkovsky drifts.Our Yarkovsky sample is the largest published set of such detections, and presents an opportunity to examine the physical properties of these NEAs and the Yarkovsky effect in a statistical manner. In particular, we confirm the Yarkovsky effect's theoretical size dependence of 1/D, where D is diameter. We also examine the efficiency with which this effect converts absorbed light into orbital drift. Using our set of 167 objects, we find typical efficiences of around 5%. This efficiency can be used to place bounds on spin and thermal properties. We report the ratio of positive to negative drift rates and interpret this ratio in terms of prograde/retrograde rotators and main belt escape mechanisms. The observed ratio has a probability of 1 in 9 million of occurring by chance, which confirms the presence of a non-gravitational influence. We examine how the presence of radar data affect the strength and precision of our detections. We find that, on average, the precision of radar+optical detections improves by a factor of approximately 1.6 for each additional apparition with ranging data compared to that of optical-only solutions.

  19. The Cost of Jointness: Insights from Environmental Monitoring Systems in Low-Earth Orbit

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, Morgan Maeve [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    This report summarizes the results of doctoral research that explored the cost impact of acquiring complex government systems jointly. The report begins by reviewing recent evidence that suggests that joint programs experience greater cost growth than non-joint programs. It continues by proposing an alternative approach for studying cost growth on government acquisition programs and demonstrates the utility of this approach by applying it to study the cost of jointness on three past programs that developed environmental monitoring systems for low-Earth orbit. Ultimately, the report concludes that joint programs' costs grow when the collaborating government agencies take action to retain or regain their autonomy. The report provides detailed qualitative and quantitative data in support of this conclusion and generalizes its findings to other joint programs that were not explicitly studied here. Finally, it concludes by presenting a quantitative model that assesses the cost impacts of jointness and by demonstrating how government agencies can more effectively architect joint programs in the future.

  20. Environmental Durability Issues for Solar Power Systems in Low Earth Orbit

    Science.gov (United States)

    Degroh, Kim K.; Banks, Bruce A.; Smith, Daniela C.

    1994-01-01

    Space solar power systems for use in the low Earth orbit (LEO) environment experience a variety of harsh environmental conditions. Materials used for solar power generation in LEO need to be durable to environmental threats such as atomic oxygen, ultraviolet (UV) radiation, thermal cycling, and micrometeoroid and debris impact. Another threat to LEO solar power performance is due to contamination from other spacecraft components. This paper gives an overview of these LEO environmental issues as they relate to space solar power system materials. Issues addressed include atomic oxygen erosion of organic materials, atomic oxygen undercutting of protective coatings, UV darkening of ceramics, UV embrittlement of Teflon, effects of thermal cycling on organic composites, and contamination due to silicone and organic materials. Specific examples of samples from the Long Duration Exposure Facility (LDEF) and materials returned from the first servicing mission of the Hubble Space Telescope (HST) are presented. Issues concerning ground laboratory facilities which simulate the LEO environment are discussed along with ground-to-space correlation issues.

  1. Near-Earth asteroid satellite spins under spin-orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Naidu, Shantanu P.; Margot, Jean-Luc [Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095 (United States)

    2015-02-01

    We develop a fourth-order numerical integrator to simulate the coupled spin and orbital motions of two rigid bodies having arbitrary mass distributions under the influence of their mutual gravitational potential. We simulate the dynamics of components in well-characterized binary and triple near-Earth asteroid systems and use surface of section plots to map the possible spin configurations of the satellites. For asynchronous satellites, the analysis reveals large regions of phase space where the spin state of the satellite is chaotic. For synchronous satellites, we show that libration amplitudes can reach detectable values even for moderately elongated shapes. The presence of chaotic regions in the phase space has important consequences for the evolution of binary asteroids. It may substantially increase spin synchronization timescales, explain the observed fraction of asychronous binaries, delay BYORP-type evolution, and extend the lifetime of binaries. The variations in spin rate due to large librations also affect the analysis and interpretation of light curve and radar observations.

  2. Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit

    Science.gov (United States)

    Bank, Bruce A.; de Groh, Kim K.; Backus, Jane A.

    2008-01-01

    A predictive tool was developed to estimate the low Earth orbit (LEO) atomic oxygen erosion yield of polymers based on the results of the Polymer Erosion and Contamination Experiment (PEACE) Polymers experiment flown as part of the Materials International Space Station Experiment 2 (MISSE 2). The MISSE 2 PEACE experiment accurately measured the erosion yield of a wide variety of polymers and pyrolytic graphite. The 40 different materials tested were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The resulting erosion yield data was used to develop a predictive tool which utilizes chemical structure and physical properties of polymers that can be measured in ground laboratory testing to predict the in-space atomic oxygen erosion yield of a polymer. The properties include chemical structure, bonding information, density and ash content. The resulting predictive tool has a correlation coefficient of 0.914 when compared with actual MISSE 2 space data for 38 polymers and pyrolytic graphite. The intent of the predictive tool is to be able to make estimates of atomic oxygen erosion yields for new polymers without requiring expensive and time consumptive in-space testing.

  3. Evaluation of Aerodynamic Drag and Torque for External Tanks in Low Earth Orbit.

    Science.gov (United States)

    Stone, William C; Witzgall, Christoph

    2006-01-01

    A numerical procedure is described in which the aerodynamic drag and torque in low Earth orbit are calculated for a prototype Space Shuttle external tank and its components, the "LO2" and "LH2" tanks, carrying liquid oxygen and hydrogen, respectively, for any given angle of attack. Calculations assume the hypersonic limit of free molecular flow theory. Each shell of revolution is assumed to be described by a series of parametric equations for their respective contours. It is discretized into circular cross sections perpendicular to the axis of revolution, which yield a series of ellipses when projected according to the given angle of attack. The drag profile, that is, the projection of the entire shell is approximated by the convex envelope of those ellipses. The area of the drag profile, that is, the drag area, and its center of area moment, that is, the drag center, are then calculated and permit determination of the drag vector and the eccentricity vector from the center of gravity of the shell to the drag center. The aerodynamic torque is obtained as the cross product of those vectors. The tanks are assumed to be either evacuated or pressurized with a uniform internal gas distribution: dynamic shifting of the tank center of mass due to residual propellant sloshing is not considered.

  4. Simulation of major space particles toward selected materials in a near-equatorial low earth orbit

    Science.gov (United States)

    Suparta, Wayan; Zulkeple, Siti Katrina

    2017-05-01

    A low earth orbit near the equator (LEO-NEqO) is exposed to the highest energies from galactic cosmic rays (GCR) and from trapped protons with a wide range of energies. Moreover, GCR fluxes were seen to be the highest in 2009 to 2010 when communication belonging to the RazakSAT-1 satellite was believed to have been lost. Hence, this study aimed to determine the influence of the space environment toward the operation of LEO-NEqO satellites by investigating the behavior of major space particles toward satellite materials. The space environment was referred to GCR protons and trapped protons. Their fluxes were obtained from the Space Environment Information System (SPENVIS) and their tracks were simulated through three materials using a simulation program called Geometry and Tracking (Geant4). The materials included aluminum (Al), gallium arsenide (GaAs) and silicon (Si). Then the total ionizing dose (TID) and non-ionizing dose (NIEL) were calculated for a three-year period. Simulations showed that GCR traveled at longer tracks and produced more secondary radiation than trapped protons. Al turned out to receive the lowest total dose, while GaAs showed to be susceptible toward GCR than Si. However, trapped protons contributed the most in spacecraft doses where Si received the highest doses. Finally, the comparison between two Geant4 programs revealed the estimated doses differed at <18%.

  5. Filament wound metal lined propellant tanks for future Earth-to-orbit transports

    Science.gov (United States)

    Macconochie, Ian O.; Davis, Robert B.; Freeman, William T., Jr.

    1988-01-01

    For future Earth-to-orbit transport vehicles, reusability and lighter weights are sought for the main propellant tanks. To achieve this, a filament wound tank with a metal liner and an intermediate layer of foam-filled honeycomb is proposed. A hydrogen tank is used as an example. To accommodate mismatches in the expansion of liner and overwrap a design is proposed wherin the liner is configured so that the extension of the liner under pressure matches the expected contraction of the same liner due to the presence of a cryogen. In operation, the liner is pressurized at a rate such that the pressure strain matches the contraction due to decrease in temperature. As an alternate approach, compressive pre-stress is placed in the liner such that it will not separate from the overwrap. A finite element program is used to show stresses in the liner and overwrap for various tank pressures for the pre-stressed liner concept. A fracture mechanics analysis is made of the liners to determine tank life. The tank concept shown has a similar weight to the Shuttle external hydrogen tank, but the filament wound tank is expected to be reusable. Integration of the propellant tanks into a future transport vehicle is discussed.

  6. The viscoelastic characterization of polymer materials exposed to the low-Earth orbit environment

    Science.gov (United States)

    Strganac, Thomas; Letton, Alan

    1992-01-01

    Recent accomplishments in our research efforts have included the successful measurement of the thermal mechanical properties of polymer materials exposed to the low-earth orbit environment. In particular, viscoelastic properties were recorded using the Rheometrics Solids Analyzer (RSA 2). Dynamic moduli (E', the storage component of the elastic modulus, and E'', the loss component of the elastic modulus) were recorded over three decades of frequency (0.1 to 100 rad/sec) for temperatures ranging from -150 to 150 C. Although this temperature range extends beyond the typical use range of the materials, measurements in this region are necessary in the development of complete viscoelastic constitutive models. The experimental results were used to provide the stress relaxation and creep compliance performance characteristics through viscoelastic correspondence principles. Our results quantify the differences between exposed and control polymer specimens. The characterization is specifically designed to elucidate a constitutive model that accurately predicts the change in behavior of these materials due to exposure. The constitutive model for viscoelastic behavior reflects the level of strain, the rate of strain, and the history of strain as well as the thermal history of the material.

  7. Orbital

    Science.gov (United States)

    Hanson, Robert M.

    2003-06-01

    ORBITAL requires the following software, which is available for free download from the Internet: Netscape Navigator, version 4.75 or higher, or Microsoft Internet Explorer, version 5.0 or higher; Chime Plug-in, version compatible with your OS and browser (available from MDL).

  8. Use of high order, periodic orbits in the PIES code

    Science.gov (United States)

    Monticello, Donald; Reiman, Allan

    2010-11-01

    We have implemented a version of the PIES code (Princeton Iterative Equilibrium SolverootnotetextA. Reiman et al 2007 Nucl. Fusion 47 572) that uses high order periodic orbits to select the surfaces on which straight magnetic field line coordinates will be calculated. The use of high order periodic orbits has increase the robustness and speed of the PIES code. We now have more uniform treatment of in-phase and out-of-phase islands. This new version has better convergence properties and works well with a full Newton scheme. We now have the ability to shrink islands using a bootstrap like current and this includes the m=1 island in tokamaks.

  9. High Latitude Dust in the Earth System

    Science.gov (United States)

    Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; hide

    2016-01-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (> or = 50degN and > or = 40degS) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 sq km and contribute at least 80-100 Tg/yr1 of dust to the Earth system (approx. 5% of the global dust budget); both are projected to increase under future climate change scenarios.

  10. 78 FR 14920 - Earth Stations Aboard Aircraft Communicating With Fixed-Satellite Service Geostationary-Orbit...

    Science.gov (United States)

    2013-03-08

    ... COMMISSION 47 CFR Parts 2 and 25 Earth Stations Aboard Aircraft Communicating With Fixed-Satellite Service... technical and licensing rules for Earth Stations Aboard Aircraft (ESAA), i.e., earth stations on aircraft...-11.2 GHz, 11.45-11.7 GHz, 11.7-12.2 GHz (space-to-Earth or downlink) and 14.0-14.5 GHz (Earth-to...

  11. A Novel Double Cluster and Principal Component Analysis-Based Optimization Method for the Orbit Design of Earth Observation Satellites

    Directory of Open Access Journals (Sweden)

    Yunfeng Dong

    2017-01-01

    Full Text Available The weighted sum and genetic algorithm-based hybrid method (WSGA-based HM, which has been applied to multiobjective orbit optimizations, is negatively influenced by human factors through the artificial choice of the weight coefficients in weighted sum method and the slow convergence of GA. To address these two problems, a cluster and principal component analysis-based optimization method (CPC-based OM is proposed, in which many candidate orbits are gradually randomly generated until the optimal orbit is obtained using a data mining method, that is, cluster analysis based on principal components. Then, the second cluster analysis of the orbital elements is introduced into CPC-based OM to improve the convergence, developing a novel double cluster and principal component analysis-based optimization method (DCPC-based OM. In DCPC-based OM, the cluster analysis based on principal components has the advantage of reducing the human influences, and the cluster analysis based on six orbital elements can reduce the search space to effectively accelerate convergence. The test results from a multiobjective numerical benchmark function and the orbit design results of an Earth observation satellite show that DCPC-based OM converges more efficiently than WSGA-based HM. And DCPC-based OM, to some degree, reduces the influence of human factors presented in WSGA-based HM.

  12. Organ shielding and doses in Low-Earth orbit calculated for spherical and anthropomorphic phantoms

    Science.gov (United States)

    Matthiä, Daniel; Berger, Thomas; Reitz, Günther

    2013-08-01

    Humans in space are exposed to elevated levels of radiation compared to ground. Different sources contribute to the total exposure with galactic cosmic rays being the most important component. The application of numerical and anthropomorphic phantoms in simulations allows the estimation of dose rates from galactic cosmic rays in individual organs and whole body quantities such as the effective dose. The male and female reference phantoms defined by the International Commission on Radiological Protection and the hermaphrodite numerical RANDO phantom are voxel implementations of anthropomorphic phantoms and contain all organs relevant for radiation risk assessment. These anthropomorphic phantoms together with a spherical water phantom were used in this work to translate the mean shielding of organs in the different anthropomorphic voxel phantoms into positions in the spherical phantom. This relation allows using a water sphere as surrogate for the anthropomorphic phantoms in both simulations and measurements. Moreover, using spherical phantoms in the calculation of radiation exposure offers great advantages over anthropomorphic phantoms in terms of computational time. In this work, the mean shielding of organs in the different voxel phantoms exposed to isotropic irradiation is presented as well as the corresponding depth in a water sphere. Dose rates for Low-Earth orbit from galactic cosmic rays during solar minimum conditions were calculated using the different phantoms and are compared to the results for a spherical water phantom in combination with the mean organ shielding. For the spherical water phantom the impact of different aluminium shielding between 1 g/cm2 and 100 g/cm2 was calculated. The dose equivalent rates were used to estimate the effective dose rate.

  13. Cosmic radiation monitoring at low-Earth orbit by means of thermoluminescence and plastic nuclear track detectors

    Czech Academy of Sciences Publication Activity Database

    Ambrožová, Iva; Pachnerová Brabcová, Kateřina; Kubančák, Ján; Šlegl, Jakub; Tolochek, R. V.; Ivanova, O. A.; Shurshakov, V. A.

    2017-01-01

    Roč. 106, č. 12 (2017), s. 262-266 ISSN 1350-4487 R&D Projects: GA ČR GJ15-16622Y Institutional support: RVO:61389005 Keywords : BION-M1 * cosmic radiation * low earth orbit * passive detector * thermoluminescent detector * plastic nuclear track detector Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.442, year: 2016

  14. IPv6 and IPsec Tests of a Space-Based Asset, the Cisco Router in Low Earth Orbit (CLEO)

    Science.gov (United States)

    Ivancic, William; Stewart, David; Wood, Lloyd; Jackson, Chris; Northam, James; Wilhelm, James

    2008-01-01

    This report documents the design of network infrastructure to support testing and demonstrating network-centric operations and command and control of space-based assets, using IPv6 and IPsec. These tests were performed using the Cisco router in Low Earth Orbit (CLEO), an experimental payload onboard the United Kingdom--Disaster Monitoring Constellation (UK-DMC) satellite built and operated by Surrey Satellite Technology Ltd (SSTL). On Thursday, 29 March 2007, NASA Glenn Research Center, Cisco Systems and SSTL performed the first configuration and demonstration of IPsec and IPv6 onboard a satellite in low Earth orbit. IPv6 is the next generation of the Internet Protocol (IP), designed to improve on the popular IPv4 that built the Internet, while IPsec is the protocol used to secure communication across IP networks. This demonstration was made possible in part by NASA s Earth Science Technology Office (ESTO) and shows that new commercial technologies such as mobile networking, IPv6 and IPsec can be used for commercial, military and government space applications. This has direct application to NASA s Vision for Space Exploration. The success of CLEO has paved the way for new spacebased Internet technologies, such as the planned Internet Routing In Space (IRIS) payload at geostationary orbit, which will be a U.S. Department of Defense Joint Capability Technology Demonstration. This is a sanitized report for public distribution. All real addressing has been changed to psueco addressing.

  15. Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit.

    Science.gov (United States)

    El-Jaby, Samy; Richardson, Richard B

    2015-07-01

    Occupational exposures from ionizing radiation are currently regulated for airline travel (Earth orbit (∼300-400 km). Aircrew typically receive between 1 and 6 mSv of occupational dose annually, while aboard the International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  16. 78 FR 14952 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...

    Science.gov (United States)

    2013-03-08

    ... COMMISSION 47 CFR Part 2 Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service... of Earth Stations Aboard Aircraft (ESAA) in the 14.0-14.5 GHz band from secondary to primary and... stations of the FSS on a primary basis in the 11.7-12.2 GHz band (space-to-Earth), on an unprotected basis...

  17. Understanding the Sun-Earth Libration Point Orbit Formation Flying Challenges For WFIRST and Starshade

    Science.gov (United States)

    Webster, Cassandra M.; Folta, David C.

    2017-01-01

    In order to fly an occulter in formation with a telescope at the Sun-Earth L2 (SEL2) Libration Point, one must have a detailed understanding of the dy-namics that govern the restricted three body system. For initial purposes, a linear approximation is satisfactory, but operations will require a high-fidelity modeling tool along with strategic targeting methods in order to be successful. This paper focuses on the challenging dynamics of the transfer trajectories to achieve the relative positioning of two spacecraft to fly in formation at SEL2, in our case, the Wide-Field Infrared Survey Telescope (WFIRST) and a proposed Starshade. By modeling the formation transfers using a high fidelity tool, an accurate V approximation can be made to as-sist with the development of the subsystem design required for a WFIRST and Starshade formation flight mission.

  18. NEUDOSE: A CubeSat Mission for Dosimetry of Charged Particles and Neutrons in Low-Earth Orbit.

    Science.gov (United States)

    Hanu, A R; Barberiz, J; Bonneville, D; Byun, S H; Chen, L; Ciambella, C; Dao, E; Deshpande, V; Garnett, R; Hunter, S D; Jhirad, A; Johnston, E M; Kordic, M; Kurnell, M; Lopera, L; McFadden, M; Melnichuk, A; Nguyen, J; Otto, A; Scott, R; Wagner, D L; Wiendels, M

    2017-01-01

    During space missions, astronauts are exposed to a stream of energetic and highly ionizing radiation particles that can suppress immune system function, increase cancer risks and even induce acute radiation syndrome if the exposure is large enough. As human exploration goals shift from missions in low-Earth orbit (LEO) to long-duration interplanetary missions, radiation protection remains one of the key technological issues that must be resolved. In this work, we introduce the NEUtron DOSimetry & Exploration (NEUDOSE) CubeSat mission, which will provide new measurements of dose and space radiation quality factors to improve the accuracy of cancer risk projections for current and future space missions. The primary objective of the NEUDOSE CubeSat is to map the in situ lineal energy spectra produced by charged particles and neutrons in LEO where most of the preparatory activities for future interplanetary missions are currently taking place. To perform these measurements, the NEUDOSE CubeSat is equipped with the Charged & Neutral Particle Tissue Equivalent Proportional Counter (CNP-TEPC), an advanced radiation monitoring instrument that uses active coincidence techniques to separate the interactions of charged particles and neutrons in real time. The NEUDOSE CubeSat, currently under development at McMaster University, provides a modern approach to test the CNP-TEPC instrument directly in the unique environment of outer space while simultaneously collecting new georeferenced lineal energy spectra of the radiation environment in LEO.

  19. Destructive physical analysis results of Ni/H[sub 2] cells cycled in low earth orbit regime (II)

    Energy Technology Data Exchange (ETDEWEB)

    Lim, H.S. (Industrial Electronics Group of Hughes Aircraft Co., Torrance, CA (United States)); Zelter, G.R. (Industrial Electronics Group of Hughes Aircraft Co., Torrance, CA (United States)); Smithrick, J.J. (NASA Lewis Research Center, Cleveland, OH (United States)); Hall, S.W. (Naval Weapons Support Center, Crane, IN (United States))

    1994-09-01

    Six 48-Ah individual pressure vessel Ni/H[sub 2] cells containing 26 and 31% KOH electrolytes have been on a low earth orbit cycle-life test. Three cells containing 31% KOH have failed after an average of 6400 cycles while the other three with 26% KOH have cycled for an average of 19 500 cycles. We have carried out post-cycle characterization tests and destructive physical analyses (DPA) of all cells. The DPA included visual inspections, measurements of electrode thickness, scanning electron microscopy, chemical analyses, and measurements of nickel electrode capacity in an electrolyte flooded cell. A gradual decrease of the usable cell capacity at high rate (1.4C) was the failure mode of all cells tested. Decrease of the usable capacity was due to decrease in the utilization of the active material with cycling mainly due to build-up of low rate capacity (residual capacity) and undischargeable active material. Cycle life of one of the cells might have been shortened prematurely due to the breakage of the cell core. Many gradual changes occurred with cycling at a rate which is independent of the KOH concentration. Each of these individual changes are difficult to be attributed to be the direct cause of the utilization decrease. However, an involved interaction of the changes might be responsible for the decrease. (orig.)

  20. Guiding Requirements for Designing Life Support System Architectures for Crewed Exploration Missions Beyond Low-Earth Orbit

    Science.gov (United States)

    Perry, Jay L.; Sargusingh, Miriam J.; Toomarian, Nikzad

    2016-01-01

    The National Aeronautics and Space Administration's (NASA) technology development roadmaps provide guidance to focus technological development in areas that enable crewed exploration missions beyond low-Earth orbit. Specifically, the technology area roadmap on human health, life support and habitation systems describes the need for life support system (LSS) technologies that can improve reliability and in-flight maintainability within a minimally-sized package while enabling a high degree of mission autonomy. To address the needs outlined by the guiding technology area roadmap, NASA's Advanced Exploration Systems (AES) Program has commissioned the Life Support Systems (LSS) Project to lead technology development in the areas of water recovery and management, atmosphere revitalization, and environmental monitoring. A notional exploration LSS architecture derived from the International Space has been developed and serves as the developmental basis for these efforts. Functional requirements and key performance parameters that guide the exploration LSS technology development efforts are presented and discussed. Areas where LSS flight operations aboard the ISS afford lessons learned that are relevant to exploration missions are highlighted.

  1. The First Neptune Analog or Super-Earth with a Neptune-Like Orbit: MOA-2013-BLG-605Lb

    Science.gov (United States)

    Sumi, T.; Bennett, D. P.; Udalski, A.; Gould, A.; Poleski, R.; Bond, I. A.; Skowron, J.; Rattenbury, N.; Pogge, R. W.; Bensby, T.

    2016-01-01

    We present the discovery of the first Neptune analog exoplanet or super-Earth with a Neptune-like orbit, MOA- 2013-BLG-605Lb. This planet has a mass similar to that of Neptune or a super-Earth and it orbits at 9 approximately 14 times the expected position of the snow line, a(sub snow), which is similar to Neptune's separation of 11 a(sub snow) from the Sun. The planet/host-star mass ratio is q = (3.6 +/- 0.7) × 10(exp -4) and the projected separation normalized by the Einstein radius is s = 2.39 +/- 0.05. There are three degenerate physical solutions and two of these are due to a new type of degeneracy in the microlensing parallax parameters, which we designate "the wide degeneracy." The three models have (i) a Neptune-mass planet with a mass of M(sub p) = 21(+6/-7)(M) orbiting a low-mass M-dwarf with a mass of M(sub h) = 0.19(+0.05/-0.06 (solar mass)), (ii) a mini-Neptune with M(sub p) = 7.9(+1.8/-1.5)(M)) orbiting a brown dwarf host with M(sub h) = 0.068(+0.019/-0.011(solar mass)), and (iii) a super-Earth with M(sub p) = 3.2(+0.5/-0.3(M)) orbiting a low-mass brown dwarf host with M(sub h) = 0.025(+0.005/-0.004)(solar mass)), which is slightly favored. The 3D planet-host separations are 4.6(+4.7/-1.2)au, 2.1(+1.0/-0.2)au, and 0.94(+0.67/-0.02)au, which are 8.9(+10.5/-1.4)m 12(+7/-1), or 14(+11/-1) times larger than a(sub snow) for these models, respectively. Keck adaptive optics observations confirm that the lens is faint. This discovery suggests that low-mass planets with Neptune-like orbits are common. Therefore processes similar to the one that formed Neptune in our own solar system or cold super-Earths may be common in other solar systems.

  2. Spacecraft orbit lifetime within two binary near-Earth asteroid systems

    Science.gov (United States)

    Damme, Friedrich; Hussmann, Hauke; Oberst, Jürgen

    2017-10-01

    We studied the motion of medium-sized and small spacecraft orbiting within the binary asteroid systems 175,706 (1996 FG3) and 65,803 Didymos (1996 GT). We have considered spacecraft motion within the binary systems distance regimes between 0.4 and 2.5 km for Didymos and 0.8-4 km for 1996 FG3. Orbital motion of spacecraft, beginning from 20,000 initial conditions lying in the orbital planes of the secondary, were simulated and evaluated for lifespan. The simulations include the effects of (1) the asteroid's mass, shape, and rotational parameters, (2) the secondary's mass and orbit parameters, (3) the spacecraft mass, surface area, and reflectivity (representing large box-wing-shaped medium-sized spacecraft as well as small satellites), and (4) the time of the mission, and therefore the relative position of the system to the sun. Stable orbital motion (i.e., not requiring thrusting maneuvers) was achieved using the Lagrange points L4/L5 and orbital resonances. This allows for long motion arcs, e.g. of 90 days (L4) and 35 days (resonance) in the Didymos system. The accuracy necessary to deploy a probe into L4, so it can remain there for 35 day, is evaluated by comparisons. Retrograde orbits were found assuring 90 days of low eccentric orbiting for a compact small satellite for a great variety of initial conditions. The comparison of simulations at aphelion and perihelion as well as the different spacecraft show the critical impact of solar radiation pressure on orbital stability. 65,803 Didymos (1996 GT) is shown to be more suitable for orbit phases at the close distances we studied compared to 175,706 (1996 FG3). Two possible obliquities of the Didymos system were considered to study the effects of the inclination on perturbing forces at equinox and solstice, showing that cases of low obliquity or times of equinox are beneficial for spacecraft orbiting.

  3. Near Earth Asteroid Rendezvous (NEAR) Revised Eros Orbit Phase Trajectory Design

    Science.gov (United States)

    Helfrich, J; Miller, J. K.; Antreasian, P. G.; Carranza, E.; Williams, B. G.; Dunham, D. W.; Farquhar, R. W.; McAdams, J. V.

    1999-01-01

    Trajectory design of the orbit phase of the NEAR mission involves a new process that departs significantly from those procedures used in previous missions. In most cases, a precise spacecraft ephemeris is designed well in advance of arrival at the target body. For NEAR, the uncertainty in the dynamic environment around Eros does not allow the luxury of a precise spacecraft trajectory to be defined in advance. The principal cause of this uncertainty is the limited knowledge oi' the gravity field a,-id rotational state of Eros. As a result, the concept for the NEAR trajectory design is to define a number of rules for satisfying spacecraft, mission, and science constraints, and then apply these rules to various assumptions for the model of Eros. Nominal, high, and low Eros mass models are used for testing the trajectory design strategy and to bracket the ranges of parameter variations that are expected upon arrival at the asteroid. The final design is completed after arrival at Eros and determination of the actual gravity field and rotational state. As a result of the unplanned termination of the deep space rendezvous maneuver on December 20, 1998, the NEAR spacecraft passed within 3830 km of Eros on December 23, 1998. This flyby provided a brief glimpse of Eros, and allowed for a more accurate model of the rotational parameters and gravity field uncertainty. Furthermore, after the termination of the deep space rendezvous burn, contact with the spacecraft was lost and the NEAR spacecraft lost attitude control. During the subsequent gyrations of the spacecraft, hydrazine thruster firings were used to regain attitude control. This unplanned thruster activity used Much of the fuel margin allocated for the orbit phase. Consequently, minimizing fuel consumption is now even more important.

  4. Abort Options for Human Missions to Earth-Moon Halo Orbits

    Science.gov (United States)

    Jesick, Mark C.

    2013-01-01

    Abort trajectories are optimized for human halo orbit missions about the translunar libration point (L2), with an emphasis on the use of free return trajectories. Optimal transfers from outbound free returns to L2 halo orbits are numerically optimized in the four-body ephemeris model. Circumlunar free returns are used for direct transfers, and cislunar free returns are used in combination with lunar gravity assists to reduce propulsive requirements. Trends in orbit insertion cost and flight time are documented across the southern L2 halo family as a function of halo orbit position and free return flight time. It is determined that the maximum amplitude southern halo incurs the lowest orbit insertion cost for direct transfers but the maximum cost for lunar gravity assist transfers. The minimum amplitude halo is the most expensive destination for direct transfers but the least expensive for lunar gravity assist transfers. The on-orbit abort costs for three halos are computed as a function of abort time and return time. Finally, an architecture analysis is performed to determine launch and on-orbit vehicle requirements for halo orbit missions.

  5. LEOcom: communication system for low earth orbit satellites for voice, data and facsimile; LEOcom - sistema de comunicacao por satelites de orbita terrestre baixa para voz, dados e facsimile

    Energy Technology Data Exchange (ETDEWEB)

    Giacaglia, G.E.O.; Lamas, W.Q. [Universidade de Taubate (UNITAU), SP (Brazil). Programa de Pos-graduacao em Engenharia Mecanica], E-mail: giorgio@unitau.br; Ceballos, D.C. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil); Pereira, J.J. [Comando-Geral de Tecnologia Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil)

    2009-07-01

    This paper provides a basic description of a Communication System for Low Earth Orbit Satellites that can provide voice, data and facsimile to hundreds of countries located in equatorial land between + and - 20 deg latitude, reaching higher latitudes, depending on the location of the onshore terminal. As a point high, it emphasizes its opportunity to support the control of networks transmission of electricity, in any area, and plants generation, located in remote areas, and support any type of operation in these regions. It is the aim of this work to reactivate a good project for Brazil and the tropical world.

  6. Wakes and differential charging of large bodies in low Earth orbit

    Science.gov (United States)

    Parker, L. W.

    1985-01-01

    Highlights of earlier results using the Inside-Out WAKE code on wake structures of LEO spacecraft are reviewed. For conducting bodies of radius large compared with the Debye length, a high Mach number wake develops a negative potential well. Quasineutrality is violated in the very near wake region, and the wake is relatively empty for a distance downstream of about one half of a Mach number of radii. There is also a suggestion of a core of high density along the axis. A comparison of rigorous numerical solutions with in situ wake data from the AE-C satellite suggests that the so called neutral approximation for ions (straight line trajectories, independent of fields) may be a reasonable approximation except near the center of the near wake. This approximation is adopted for very large bodies. Work concerned with the wake point potential of very large nonconducting bodies such as the shuttle orbiter is described. Using a cylindrical model for bodies of this size or larger in LEO (body radius up to 10 to the 5th power Debye lengths), approximate solutions are presented based on the neutral approximation (but with rigorous trajectory calculations for surface current balance). There is a negative potential well if the body is conducting, and no well if the body is nonconducting. In the latter case the wake surface itself becomes highly negative. The wake point potential is governed by the ion drift energy.

  7. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Directory of Open Access Journals (Sweden)

    S. Schweitzer

    2011-10-01

    Full Text Available LEO-LEO infrared-laser occultation (LIO is a new occultation technique between Low Earth Orbit (LEO satellites, which applies signals in the short wave infrared spectral range (SWIR within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We

  8. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Science.gov (United States)

    Schweitzer, S.; Kirchengast, G.; Proschek, V.

    2011-10-01

    LEO-LEO infrared-laser occultation (LIO) is a new occultation technique between Low Earth Orbit (LEO) satellites, which applies signals in the short wave infrared spectral range (SWIR) within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO) method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity) and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms) of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We conclude that

  9. Low Earth orbit assessment of proton anisotropy using AP8 and AP9 trapped proton models.

    Science.gov (United States)

    Badavi, Francis F; Walker, Steven A; Santos Koos, Lindsey M

    2015-04-01

    The completion of the International Space Station (ISS) in 2011 has provided the space research community with an ideal evaluation and testing facility for future long duration human activities in space. Ionized and secondary neutral particles radiation measurements inside ISS form the ideal tool for validation of radiation environmental models, nuclear reaction cross sections and transport codes. Studies using thermo-luminescent detectors (TLD), tissue equivalent proportional counter (TPEC), and computer aided design (CAD) models of early ISS configurations confirmed that, as input, computational dosimetry at low Earth orbit (LEO) requires an environmental model with directional (anisotropic) capability to properly describe the exposure of trapped protons within ISS. At LEO, ISS encounters exposure from trapped electrons, protons and geomagnetically attenuated galactic cosmic rays (GCR). For short duration studies at LEO, one can ignore trapped electrons and ever present GCR exposure contributions during quiet times. However, within the trapped proton field, a challenge arises from properly estimating the amount of proton exposure acquired. There exist a number of models to define the intensity of trapped particles. Among the established trapped models are the historic AE8/AP8, dating back to the 1980s and the recently released AE9/AP9/SPM. Since at LEO electrons have minimal exposure contribution to ISS, this work ignores the AE8 and AE9 components of the models and couples a measurement derived anisotropic trapped proton formalism to omnidirectional output from the AP8 and AP9 models, allowing the assessment of the differences between the two proton models. The assessment is done at a target point within the ISS-11A configuration (circa 2003) crew quarter (CQ) of Russian Zvezda service module (SM), during its ascending and descending nodes passes through the south Atlantic anomaly (SAA). The anisotropic formalism incorporates the contributions of proton narrow

  10. Orbital Transfer Vehicle (space taxi) with aerobraking at Earth and Mars

    Science.gov (United States)

    1987-01-01

    This report shall cover all major aspects of the design of an Aeroassisted Manned Transfer Vehicle (or TAXI) for use as part of advanced manned Mars missions based on a cycling ship concept. Along with the heliocentric orbiting Cycling Spacecraft, such a TAXI would be a primary component of a long-term transportation system for Mars exploration. The Aeroassisted Manned Transfer Vehicle (AMTV) design developed shall operate along transfer trajectories between Earth and a Cycling Spacecraft (designed by the University of Michigan) and Mars. All operations of the AMTV shall be done primarily within the sphere of influence of the two planets. Maximum delta-V's for the vehicle have been established near 9 km/sec, with transfer durations of about 3 days. Acceleration deltaV's will be accomplished using 3 SSME-based hydrogen-oxygen chemical rockets (l(sub sp) = 485 sec & Thrust greater than = 300,00 Ib(sub f)/engine) with a thrust vector directly opposite the aerobraking deceleration vector. The aerobraking deceleration portion of an AMTV mission would be accomplished in this design by a moderate L/D aeroshield of an ellipsoidally-blunt, raked-off, elliptic cone (EBROEC) shape. The reusable thermal protection material comprising the shield will consist of a flexible, multi-layer, ceramic fabric stretched over a lightweight, rigid, shape - defining truss structure. Behind this truss, other components, including the engine supports, would be attached and protected from heating during aerobraking passes. Among these other components would be 2 LOX tanks and 4 LH2 tanks (and their support frames) holding over 670,000 lbm of propellant necessary to impart the required delta-V to the 98,000 lbm burnout mass vehicle. A 20,000 lbm crew module with docking port (oriented parallel to the accel./decel. axis) will provide accommodations for 9 crew members (11 under extreme conditions) for durations up to seven days, thus allowing extra time for emergency situations. This AMTV will be

  11. Study on High Resolution Membrane-Based Diffractive Optical Imaging on Geostationary Orbit

    Science.gov (United States)

    Jiao, J.; Wang, B.; Wang, C.; Zhang, Y.; Jin, J.; Liu, Z.; Su, Y.; Ruan, N.

    2017-05-01

    Diffractive optical imaging technology provides a new way to realize high resolution earth observation on geostationary orbit. There are a lot of benefits to use the membrane-based diffractive optical element in ultra-large aperture optical imaging system, including loose tolerance, light weight, easy folding and unfolding, which make it easy to realize high resolution earth observation on geostationary orbit. The implementation of this technology also faces some challenges, including the configuration of the diffractive primary lens, the development of high diffraction efficiency membrane-based diffractive optical elements, and the correction of the chromatic aberration of the diffractive optical elements. Aiming at the configuration of the diffractive primary lens, the "6+1" petal-type unfold scheme is proposed, which consider the compression ratio, the blocking rate and the development complexity. For high diffraction efficiency membrane-based diffractive optical element, a self-collimating method is proposed. The diffraction efficiency is more than 90 % of the theoretical value. For the chromatic aberration correction problem, an optimization method based on schupmann is proposed to make the imaging spectral bandwidth in visible light band reach 100 nm. The above conclusions have reference significance for the development of ultra-large aperture diffractive optical imaging system.

  12. A MATLAB based Distributed Real-time Simulation of Lander-Orbiter-Earth Communication for Lunar Missions

    Science.gov (United States)

    Choudhury, Diptyajit; Angeloski, Aleksandar; Ziah, Haseeb; Buchholz, Hilmar; Landsman, Andre; Gupta, Amitava; Mitra, Tiyasa

    Lunar explorations often involve use of a lunar lander , a rover [1],[2] and an orbiter which rotates around the moon with a fixed radius. The orbiters are usually lunar satellites orbiting along a polar orbit to ensure visibility with respect to the rover and the Earth Station although with varying latency. Communication in such deep space missions is usually done using a specialized protocol like Proximity-1[3]. MATLAB simulation of Proximity-1 have been attempted by some contemporary researchers[4] to simulate all features like transmission control, delay etc. In this paper it is attempted to simulate, in real time, the communication between a tracking station on earth (earth station), a lunar orbiter and a lunar rover using concepts of Distributed Real-time Simulation(DRTS).The objective of the simulation is to simulate, in real-time, the time varying communication delays associated with the communicating elements with a facility to integrate specific simulation modules to study different aspects e.g. response due to a specific control command from the earth station to be executed by the rover. The hardware platform comprises four single board computers operating as stand-alone real time systems (developed by MATLAB xPC target and inter-networked using UDP-IP protocol). A time triggered DRTS approach is adopted. The earth station, the orbiter and the rover are programmed as three standalone real-time processes representing the communicating elements in the system. Communication from one communicating element to another constitutes an event which passes a state message from one element to another, augmenting the state of the latter. These events are handled by an event scheduler which is the fourth real-time process. The event scheduler simulates the delay in space communication taking into consideration the distance between the communicating elements. A unique time synchronization algorithm is developed which takes into account the large latencies in space

  13. Atmospheric attenuation relative to earth-viewing orbital sensors. [atmospheric moisture effects on microwaves

    Science.gov (United States)

    Brown, S. C.; Jayroe, R. R., Jr.

    1973-01-01

    Earth viewing space missions offer exciting new possibilities in several earth resources disciplines - geography, hydrology, agriculture, geology, and oceanography, to name a few. A most useful tool in planning experiments and applying space technology to earth observation is a statistical description of atmospheric parameters. Four dimensional atmospheric models and a world wide cloud model are used to produce atmospheric attenuation models to predict degradation effects for all classes of sensors for application to earth sensing experiments from spaceborne platforms. To insure maximum utility and application of these products, the development of an interaction model of microwave energy and atmospheric variables provides a complete description of the effects of atmospheric moisture upon microwaves.

  14. Orbit Determination (OD) Error Analysis Results for the Triana Sun-Earth L1 Libration Point Mission and for the Fourier Kelvin Stellar Interferometer (FKSI) Sun-Earth L2 Libration Point Mission Concept

    Science.gov (United States)

    Marr, Greg C.

    2003-01-01

    The Triana spacecraft was designed to be launched by the Space Shuttle. The nominal Triana mission orbit will be a Sun-Earth L1 libration point orbit. Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination (OD) error analysis results are presented for all phases of the Triana mission from the first correction maneuver through approximately launch plus 6 months. Results are also presented for the science data collection phase of the Fourier Kelvin Stellar Interferometer Sun-Earth L2 libration point mission concept with momentum unloading thrust perturbations during the tracking arc. The Triana analysis includes extensive analysis of an initial short arc orbit determination solution and results using both Deep Space Network (DSN) and commercial Universal Space Network (USN) statistics. These results could be utilized in support of future Sun-Earth libration point missions.

  15. Three Dimensional Orbital Stability About the Earth-Moon Equilateral Libration Points.

    Science.gov (United States)

    1980-12-01

    APPROVED F3:R FASE AFR 19017. alv, t ! r LAUREL A. LANPELA, 2Lt, SAF Deputy Director, Public Affairs Aui Fi : h c, Tcdms!ogy (ATC) W , . - , UOil 45433...length of stability. * The orbit is found to have a stable lifetime in excess of six hundred lunar synodic months. The sensitivity of the orbit to the...one lunar synodic month. See Fig 3 for a representation of the Wheeler system and Fig 4 for the predicted Wheeler orbit. The initial coLdiL ip s ,re

  16. Design and Applications of Solar Sail Periodic Orbits in the Non-Autonomous Earth-Moon System

    NARCIS (Netherlands)

    Heiligers, M.J.; Macdonald, Malcolm; Parker, Jeffrey S.; Turner, J.D.; Wawrzyniak, G.G.; Cerven, W.T.; Majji, M.

    2015-01-01

    Solar sailing has great potential for a range of high-energy and long duration mis-sions in the Sun-Earth system. This paper extends this potential to the non-autonomous Earth-Moon system through the use of a differential correction scheme, and by selecting suitable in-plane and out-of-plane sail

  17. The International Space Station: A Low-Earth Orbit (LEO) Test Bed for Advancements in Space and Environmental Medicine

    Science.gov (United States)

    Ruttley, Tara M.; Robinson, Julie A.

    2010-01-01

    Ground-based space analog projects such as the NASA Extreme Environment Mission Operations (NEEMO) can be valuable test beds for evaluation of experimental design and hardware feasibility before actually being implemented on orbit. The International Space Station (ISS) is an closed-system laboratory that orbits 240 miles above the Earth, and is the ultimate extreme environment. Its inhabitants spend hours performing research that spans from fluid physics to human physiology, yielding results that have implications for Earth-based improvements in medicine and health, as well as those that will help facilitate the mitigation of risks to the human body associated with exploration-class space missions. ISS health and medical experiments focus on pre-flight and in-flight prevention, in-flight treatment, and postflight recovery of health problems associated with space flight. Such experiments include those on enhanced medical monitoring, bone and muscle loss prevention, cardiovascular health, immunology, radiation and behavior. Lessons learned from ISS experiments may not only be applicable to other extreme environments that face similar capability limitations, but also serve to enhance standards of care for everyday use on Earth.

  18. Orbital Dynamics of Planetary Systems with Super-Earths and Mini-Neptunes

    Science.gov (United States)

    Ford, E. B.; Carrera, D.; Jontof-Hutter, D.; Lissuer, J. J.; Rogers, L. A.; Wolfgang, A.

    2017-11-01

    Planet formation directly determines various properties of planets that impact their habitability. I propose to review the orbital dynamics of exoplanetary systems, emphasizing the implications for characteristics likely to impact habitability.

  19. Traverses for lunar rovers and sample return teleoperated from Earth or cislunar orbit

    Science.gov (United States)

    Kamps, Oscar; Foing, Bernard H.; Flahaut, Jessica

    2016-07-01

    Most interesting sites for exploration are near the poles of the Moon where water and other ices and volatiles could be stable in the permanent shaded regions. Several instruments on multiple orbiters have indicated the presence of hydrogen or hydration but the relation with the illumination conditions are not as clear. Which other variables are involved to trap water near the poles is not known. This ignorance makes it of high interest to do in-situ research on the Moon. ESA, NASA and other agencies are studying a teleoperated mission from cislunar orbit with Orion (eg. HERACLES international lunar exploration architecture) with the possibility of long rover traverses, and human assisted sample return. This mission concept was used for this study on a rover traverse. This study focuses on both the North as South Pole. The site selection for a traverse was based on the temperature map from Diviner. Regions of interests were made as primary selection and cover areas where the maximum temperature is lower than the sublimation temperature of CO2. Data from neutron spectrometer from the Prospector, and crater epoch according to the USGS were used to make a selection of regions of interest. These selected sites where studied on their accessibility for a rover, based on the slope map made from the LOLA elevation model. A landing site was selected based on assumptions that it should be at least one kilometre in diameter and have a slope lower than 5 degrees. The temperature difference (Tmax-Tmin from the Diviner measurements) was used select a scientifically interesting site between the landing site and destination inside a PSR. It was thought that a site with a temperature difference larger than 150K is interesting to study volatile migration processes. Eventually for the traverse planning a tool in ArcGIS was used which calculates the easiest from one location to another where the slope is used as limiting factor. We give the example study of rover traverse planning

  20. Utilization of landmark data in attitude/orbit determination. [for earth stabilized satellites

    Science.gov (United States)

    Siddalingaiah, H.; Desai, P. S.

    1975-01-01

    A mathematical model is reported for determination of satellite position, velocity, and attitude using landmark coordinates as observables. This model, although developed with respect to earth stabilized missions, Tiros-N and Nimbus-G in particular, is applicable to any earth stabilized satellite in general.

  1. 78 FR 19172 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...

    Science.gov (United States)

    2013-03-29

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Parts 2 and 25 Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service... proposed rule that appeared in the Federal Register of March 8, 2013. The document proposed rules for Earth...

  2. Survival of akinetes (resting-state cells of cyanobacteria) in low earth orbit and simulated extraterrestrial conditions.

    Science.gov (United States)

    Olsson-Francis, Karen; de la Torre, Rosa; Towner, Martin C; Cockell, Charles S

    2009-12-01

    Cyanobacteria are photosynthetic organisms that have been considered for space applications, such as oxygen production in bioregenerative life support systems, and can be used as a model organism for understanding microbial survival in space. Akinetes are resting-state cells of cyanobacteria that are produced by certain genera of heterocystous cyanobacteria to survive extreme environmental conditions. Although they are similar in nature to endospores, there have been no investigations into the survival of akinetes in extraterrestrial environments. The aim of this work was to examine the survival of akinetes from Anabaena cylindrica in simulated extraterrestrial conditions and in Low Earth Orbit (LEO). Akinetes were dried onto limestone rocks and sent into LEO for 10 days on the ESA Biopan VI. In ground-based experiments, the rocks were exposed to periods of desiccation, vacuum (0.7×10(-3) kPa), temperature extremes (-80 to 80°C), Mars conditions (-27°C, 0.8 kPa, CO(2)) and UV radiation (325-400 nm). A proportion of the akinete population was able to survive a period of 10 days in LEO and 28 days in Mars simulated conditions, when the rocks were not subjected to UV radiation. Furthermore, the akinetes were able to survive 28 days of exposure to desiccation and low temperature with high viability remaining. Yet long periods of vacuum and high temperature were lethal to the akinetes. This work shows that akinetes are extreme-tolerating states of cyanobacteria that have a practical use in space applications and yield new insight into the survival of microbial resting-state cells in space conditions.

  3. Attitude and orbital dynamics modeling for an uncontrolled solar-sail experiment in low-Earth orbit

    NARCIS (Netherlands)

    Pirovano, L.; Seefeldt, P.; Dachwald, B.; Noomen, R.

    2015-01-01

    Gossamer-1 is the first project of the three-step Gossamer roadmap, the purpose of which is to develop, prove and demonstrate that solar-sail technology is a safe and reliable propulsion technique for long-lasting and high-energy missions. This paper firstly presents the structural analysis

  4. Automated anomaly detection for Orbiter High Temperature Reusable Surface Insulation

    Science.gov (United States)

    Cooper, Eric G.; Jones, Sharon M.; Goode, Plesent W.; Vazquez, Sixto L.

    1992-01-01

    The description, analysis, and experimental results of a method for identifying possible defects on High Temperature Reusable Surface Insulation (HRSI) of the Orbiter Thermal Protection System (TPS) is presented. Currently, a visual postflight inspection of Orbiter TPS is conducted to detect and classify defects as part of the Orbiter maintenance flow. The objective of the method is to automate the detection of defects by identifying anomalies between preflight and postflight images of TPS components. The initial version is intended to detect and label gross (greater than 0.1 inches in the smallest dimension) anomalies on HRSI components for subsequent classification by a human inspector. The approach is a modified Golden Template technique where the preflight image of a tile serves as the template against which the postflight image of the tile is compared. Candidate anomalies are selected as a result of the comparison and processed to identify true anomalies. The processing methods are developed and discussed, and the results of testing on actual and simulated tile images are presented. Solutions to the problems of brightness and spatial normalization, timely execution, and minimization of false positives are also discussed.

  5. High Performance Orbital Propagation Using a Generic Software Architecture

    Science.gov (United States)

    Möckel, M.; Bennett, J.; Stoll, E.; Zhang, K.

    2016-09-01

    Orbital propagation is a key element in many fields of space research. Over the decades, scientists have developed numerous orbit propagation algorithms, often tailored to specific use cases that vary in available input data, desired output as well as demands of execution speed and accuracy. Conjunction assessments, for example, require highly accurate propagations of a relatively small number of objects while statistical analyses of the (untracked) space debris population need a propagator that can process large numbers of objects in a short time with only medium accuracy. Especially in the latter case, a significant increase of computation speed can be achieved by using graphics processors, devices that are designed to process hundreds or thousands of calculations in parallel. In this paper, an analytical propagator is introduced that uses graphics processing to reduce the run time for propagating a large space debris population from several hours to minutes with only a minor loss of accuracy. A second performance analysis is conducted on a parallelised version of the popular SGP4 algorithm. It is discussed how these modifications can be applied to more accurate numerical propagators. Both programs are implemented using a generic, plugin-based software architecture designed for straightforward integration of propagators into other software tools. It is shown how this architecture can be used to easily integrate, compare and combine different orbital propagators, both CPU and GPU-based.

  6. On-Orbit Camera Misalignment Estimation Framework and Its Application to Earth Observation Satellite

    Directory of Open Access Journals (Sweden)

    Seungwoo Lee

    2015-03-01

    Full Text Available Despite the efforts for precise alignment of imaging sensors and attitude sensors before launch, the accuracy of pre-launch alignment is limited. The misalignment between attitude frame and camera frame is especially important as it is related to the localization error of the spacecraft, which is one of the essential factors of satellite image quality. In this paper, a framework for camera misalignment estimation is presented with its application to a high-resolution earth-observation satellite—Deimos-2. The framework intends to provide a solution for estimation and correction of the camera misalignment of a spacecraft, covering image acquisition planning to mathematical solution of camera misalignment. Considerations for effective image acquisition planning to obtain reliable results are discussed, followed by a detailed description on a practical method for extracting many GCPs automatically using reference ortho-photos. Patterns of localization errors that commonly occur due to the camera misalignment are also investigated. A mathematical model for camera misalignment estimation is described comprehensively. The results of simulation experiments showing the validity and accuracy of the misalignment estimation model are provided. The proposed framework was applied to Deimos-2. The real-world data and results from Deimos-2 are presented.

  7. Senior High School Earth Sciences and Marine Sciences.

    Science.gov (United States)

    Hackenberg, Mary; And Others

    This guide was developed for earth sciences and marine sciences instruction in the senior high schools of Duval County, Jacksonville, Florida. The subjects covered are: (1) Earth Science for 10th, 11th, and 12th graders; (2) Marine Biology I for 10th, 11th, and 12th graders; (3) Marine Biology II, Advanced, for 11th and 12th graders; (4) Marine…

  8. Military Applications of High-Altitude Satellite Orbits in a Multi-Body Dynamical Environment Using Numerical Methods and Dynamical Systems Theory

    Science.gov (United States)

    2016-03-01

    multi-body dynamical model. Other potential applications of the tools in the present investigation include mis - sions that start in the near-Earth...MILITARY APPLICATIONS OF HIGH-ALTITUDE SATELLITE ORBITS IN A MULTI-BODY DYNAMICAL ENVIRONMENT USING NUMERICAL METHODS AND DYNAMICAL SYSTEMS THEORY...16-M-247 MILITARY APPLICATIONS OF HIGH-ALTITUDE SATELLITE ORBITS IN A MULTI-BODY DYNAMICAL ENVIRONMENT USING NUMERICAL METHODS AND DYNAMICAL SYSTEMS

  9. NASA Earth-to-Orbit Engineering Design Challenges: Thermal Protection Systems

    Science.gov (United States)

    National Aeronautics and Space Administration (NASA), 2010

    2010-01-01

    National Aeronautics and Space Administration (NASA) Engineers at Marshall Space Flight Center, Dryden Flight Research Center, and their partners at other NASA centers and in private industry are currently developing X-33, a prototype to test technologies for the next generation of space transportation. This single-stage-to-orbit reusable launch…

  10. In-orbit assessment of laser retro-reflector efficiency onboard high orbiting satellites

    Science.gov (United States)

    Wilkinson, Matthew; Appleby, Graham

    2011-08-01

    The navigation and geodetic satellites that orbit the Earth at altitudes of approximately 20,000 km are tracked routinely by many of the Satellite Laser Ranging (SLR) stations of the International Laser Ranging Service (ILRS). In order to meet increasing demands on SLR stations for daytime and nighttime observations, any new mission needs to ensure a strong return signal so that the target is easily acquirable. The ILRS has therefore set a minimum effective cross-section of 100 million square metres for the on-board laser retro-reflector arrays (LRAs) and further recommends the use of 'uncoated' cubes in the arrays. Given the large number of GNSS satellites that are currently supported by SLR, it is informative to make an assessment of the relative efficiencies of the various LRAs employed. This paper uses the laser ranging observations themselves to deduce and then compare the efficiencies of the LRAs on the COMPASS-M1 navigation satellite, two satellites from the GPS and three from the GLONASS constellations, the two GIOVE test satellites from the upcoming Galileo constellation, the two Etalon geodetic spheres and the geosynchronous communications test satellite, ETS-8. All the LRAs on this set of satellites employ back-coated retro-reflector cubes, except those on the COMPASS-M1 and ETS-8 vehicles which are uncoated. A measure of return signal strength, and thus of LRA-efficiency, is calculated using the laser-range full-rate data archive from 2007 to 2010, scaled to remove the effects of variations in satellite range, atmospheric attenuation and retro-reflector target total surface area. Observations from five SLR stations are used in this study; they are Herstmonceux (UK), Yarragadee (Australia), Monument Peak and McDonald (USA) and Wettzell (Germany). Careful consideration is given to the treatment of the observations from each station in order to take account of local working practices and system upgrades. The results show that the uncoated retro

  11. Feasibility Study for Measuring Geomagnetic Conversion of Solar Axions to X-rays in Low Earth Orbits

    CERN Document Server

    Davoudiasl, Hooman

    2008-01-01

    We present a detailed computation of the expected rate for Geomagnetic Conversion of Solar Axions to X-rays (GECOSAX) along the orbit of an x-ray satellite. We use realistic satellite orbits and propagation in time. A realistic model for the Earth's magnetic field, which properly accounts for its spatial non-uniformity, is used. We also account for the effect of the Earth's atmosphere on the propagation of x-rays in our calculation of axion-photon conversion probability. To estimate possible sensitivities to the axion-photon coupling g_{a\\gamma}, we use an actual measurement of the expected backgrounds by the SUZAKU satellite. Assuming a detector area of 10^3 cm^2 and about 10^6 s of data, we show that a 2 \\sigma limit of g_{a\\gamma} < (4.7-6.6) times 10^{-11} GeV^{-1} from GECOSAX is achievable, for axion masses m_a<10^{-4} eV. This significantly exceeds current laboratory sensitivities to g_{a\\gamma}.

  12. The AMSAT-OSCAR-40 High Elliptical Orbit Radiation Environment Monitoring Payload - First Flight Results

    Science.gov (United States)

    Sweeting, Martin, , Sir

    Over the last decade, Surrey's micro-satellites have provided continuous monitoring of the proton and heavy-ion environment encountered in low-Earth orbit (LEO), through the use of a series of silicon PIN-diode-based particle detectors, starting with the UK Defence Evaluation Research Agency's (DERA's) Cosmic-Radiation Environment and Dosimetry (CREDO) payload, flown on-board UoSAT-3 in 1990, followed in 1992 by the Cosmic-Ray Experiment (CRE), developed at the Surrey Space Centre under a micro-satellite Technology Transfer (TT) programme operated between Surrey Satellite Technology Ltd. (SSTL) and the Korea Advanced Institute of Science and Technology (KAIST), and flown on the resulting KITSAT-1 micro-satellite. The CRE was flown again in 1993 on-board the PoSAT- 1 micro-satellite, developed under a similar TT programme operated between SSTL and Portugal. The results from all of these instruments have given a great deal of information on the nature of the low-Earth orbit (LEO) ionising radiation environment, and in the case of the PoSAT-1 CRE, continue to do so. However, to obtain a more complete "picture" of the magnetosphere, it is necessary to orbit instruments much further out in space An opportunity to do this arose in 1994 when amateur radio satellite groups (AMSAT) proposed launching a small (600 kg) communications satellite into highly elliptical orbit. This satellite, called AMSAT-OSCAR-40 (AO-40), was launched by Ariane 5 rocket on 16th November 2000, initially into a geostationary transfer orbit (GTO). The satellite has subsequently been manoeuvred into a highly elliptical, 1070 km x 58,700 km, 6.8o inclination orbit, and thus it affords the opportunity to observe the proton and heavy-ion environment through a large cross-section of Earth's magnetosphere. AO-40 carries a version of the CRE, which has been slightly modified in terms of interfaces and packaging to fit that particular satellite bus. However the particle detecting element is essentially

  13. Neutron Measurements for Radiation Protection in Low Earth Orbit - History and Future

    Science.gov (United States)

    Golightly, M. J.; Se,pmes. E/

    2003-01-01

    The neutron environment inside spacecraft has been of interest from a scientific and radiation protection perspective since early in the history of manned spaceflight. With 1:.1e exception of a few missions which carried plutonium-fueled radioisotope thermoelectric generators, all of the neutrons inside the spacecraft are secondary radiations resulting from interactions of high-energy charged particles with nuclei in the Earth's atmosphere, spacecraft structural materials, and the astronaut's own bodies. Although of great interest, definitive measurements of the spacecraft neutron field have been difficult due to the wide particle energy range and the limited available volume and power for traditional techniques involving Bonner spheres. A multitude of measurements, however, have been made of the neutron environment inside spacecraft. The majority of measurements were made using passive techniques including metal activation fo ils, fission foils, nuclear photoemulsions, plastic track detectors, and thermoluminescent detectors. Active measurements have utilized proton recoil spectrometers (stilbene), Bonner Spheres eRe proportional counter based), and LiI(Eu)phoswich scintillation detectors. For the International Space Station (ISS), only the plastic track! thermoluminescent detectors are used with any regularity. A monitoring program utilizing a set of active Bonner spheres was carried out in the ISS Lab module from March - December 200l. These measurements provide a very limited look at the crew neutron exposure, both in time coverage and neutron energy coverage. A review of the currently published data from past flights will be made and compared with the more recent results from the ISS. Future measurement efforts using currently available techniques and those in development will be also discussed.

  14. Analysis of the Effect of UTI-UTC to High Precision Orbit Propagation

    Directory of Open Access Journals (Sweden)

    Dongseok Shin

    1999-12-01

    Full Text Available As the spatial resolution of remote sensing satellites becomes higher, very accurate determination of the position of a LEO (Low Earth Orbit satellite is demanding more than ever. Non-symmetric Earth gravity is the major perturbation force to LEO satellites. Since the orbit propagation is performed in the celestial frame while Earth gravity is defined in the terrestrial frame, it is required to convert the coordinates of the satellite from one to the other accurately. Unless the coordinate conversion between the two frames is performed accurately the orbit propagation calculates incorrect Earth gravitational force at a specific time instant, and hence, causes errors in orbit prediction. The coordinate conversion between the two frames involves precession, nutation, Earth rotation and polar motion. Among these factors, unpredictability and uncertainty of Earth rotation, called UTI-UTC, is the largest error source. In this paper, the effect of UTI-UTC on the accuracy of the LEO propagation is introduced, tested and analzed. Considering the maximum unpredictability of UTI-UTC, 0.9 seconds, the meaningful order of non-spherical Earth harmonic functions is derived.

  15. Bringing Earth Magnetism Research into the High School Physics Classroom

    Science.gov (United States)

    Smirnov, A. V.; Bluth, G.; Engel, E.; Kurpier, K.; Foucher, M. S.; Anderson, K. L.

    2015-12-01

    We present our work in progress from an NSF CAREER project that aims to integrate paleomagnetic research and secondary school physics education. The research project is aimed at quantifying the strength and geometry of the Precambrian geomagnetic field. Investigation of the geomagnetic field behavior is crucial for understanding the mechanisms of field generation, and the development of the Earth's atmosphere and biosphere, and can serve as a focus for connecting high-level Earth science research with a standard physics curriculum. High school science teachers have participated in each summer field and research component of the project, gaining field and laboratory research experience, sets of rock and mineral samples, and classroom-tested laboratory magnetism activities for secondary school physics and earth science courses. We report on three field seasons of teacher field experiences and two years of classroom testing of paleomagnetic research materials merged into physics instruction on magnetism. Students were surveyed before and after dedicated instruction for both perceptions and attitude towards earth science in general, then more specifically on earth history and earth magnetism. Students were also surveyed before and after instruction on major earth system and magnetic concepts and processes, particularly as they relate to paleomagnetic research. Most students surveyed had a strongly positive viewpoint towards the study of Earth history and the importance of studying Earth Sciences in general, but were significantly less drawn towards more specific topics such as mineralogy and magnetism. Students demonstrated understanding of Earth model and the basics of magnetism, as well as the general timing of life, atmospheric development, and magnetic field development. However, detailed knowledge such as the magnetic dynamo, how the magnetic field has changed over time, and connections between earth magnetism and the development of an atmosphere remained largely

  16. Investigation of organic magnetoresistance dependence on spin-orbit coupling using 8-hydroxyquinolinate rare-earth based complexes

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, R. S.; Ávila, H. C.; Cremona, M., E-mail: cremona@fis.puc-rio.br [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 22451-900 (Brazil); Costa, D. G. [Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil); Departamento de Química, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900 (Brazil); Paolini, T. B.; Brito, H. F. [Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000 (Brazil); Capaz, Rodrigo B. [Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil)

    2016-05-16

    The recently discovered organic magnetoresistance effect (OMAR) reveals the spin-dependent behavior of the charge transport in organic semiconductors. So far, it is known that hyperfine interactions play an important role in this phenomenon and also that spin-orbit coupling is negligible for light-atom based compounds. However, in the presence of heavy atoms, spin-orbit interactions should play an important role in OMAR. It is known that these interactions are responsible for singlet and triplet states mixing via intersystem crossing and the change of spin-charge relaxation time in the charge mobility process. In this work, we report a dramatic change in the OMAR effect caused by the presence of strong intramolecular spin-orbit coupling in a series of rare-earth quinolate organic complex-based devices. Our data show a different OMAR lineshape compared with the OMAR lineshape of tris(8-hydroxyquinolinate) aluminum-based devices, which are well described in the literature. In addition, electronic structure calculations based on density functional theory help to establish the connection between this results and the presence of heavy central ions in the different complexes.

  17. Ionosphere Plasma State Determination in Low Earth Orbit from International Space Station Plasma Monitor

    Science.gov (United States)

    Kramer, Leonard

    2014-01-01

    A plasma diagnostic package is deployed on the International Space Station (ISS). The system - a Floating Potential Measurement Unit (FPMU) - is used by NASA to monitor the electrical floating potential of the vehicle to assure astronaut safety during extravehicular activity. However, data from the unit also reflects the ionosphere state and seems to represent an unutilized scientific resource in the form of an archive of scientific plasma state data. The unit comprises a Floating Potential probe and two Langmuir probes. There is also an unused but active plasma impedance probe. The data, at one second cadence, are collected, typically for a two week period surrounding extravehicular activity events. Data is also collected any time a visiting vehicle docks with ISS and also when any large solar events occur. The telemetry system is unusual because the package is mounted on a television camera stanchion and its data is impressed on a video signal that is transmitted to the ground and streamed by internet to two off center laboratory locations. The data quality has in the past been challenged by weaknesses in the integrated ground station and distribution systems. These issues, since mid-2010, have been largely resolved and the ground stations have been upgraded. Downstream data reduction has been developed using physics based modeling of the electron and ion collecting character in the plasma. Recursive algorithms determine plasma density and temperature from the raw Langmuir probe current voltage sweeps and this is made available in real time for situational awareness. The purpose of this paper is to describe and record the algorithm for data reduction and to show that the Floating probe and Langmuir probes are capable of providing long term plasma state measurement in the ionosphere. Geophysical features such as the Appleton anomaly and high latitude modulation at the edge of the Auroral zones are regularly observed in the nearly circular, 51 deg inclined, 400 km

  18. Orbital maneuvers between the Lagrangian points and the primaries in the Earth-Sun system

    OpenAIRE

    Prado, Antônio F. B. Almeida

    2006-01-01

    This paper is concerned with trajectories to transfer a spacecraft between the Lagrangian points of the Sun-Earth system and the primaries. The Lagrangian points have important applications in astronautics, since they are equilibrium points of the equation of motion and very good candidates to locate a satellite or a space station. The planar circular restricted three-body problem in two dimensions is used as the model for the Sun-Earth system, and Lamaître regularization is used to avoid sin...

  19. Compact and high-resolution optical orbital angular momentum sorter

    Directory of Open Access Journals (Sweden)

    Chenhao Wan

    2017-03-01

    Full Text Available A compact and high-resolution optical orbital angular momentum (OAM sorter is proposed and demonstrated. The sorter comprises a quadratic fan-out mapper and a dual-phase corrector positioned in the pupil plane and the Fourier plane, respectively. The optical system is greatly simplified compared to previous demonstrations of OAM sorting, and the performance in resolution and efficiency is maintained. A folded configuration is set up using a single reflective spatial light modulator (SLM to demonstrate the validity of the scheme. The two phase elements are implemented on the left and right halves of the SLM and connected by a right-angle prism. Experimental results demonstrate the high resolution of the compact OAM sorter, and the current limit in efficiency can be overcome by replacing with transmissive SLMs and removing the beam splitters. This novel scheme paves the way for the miniaturization and integration of high-resolution OAM sorters.

  20. Space Debris Detection in Low Earth Orbit with the Sardinia Radio Telescope

    Directory of Open Access Journals (Sweden)

    Giacomo Muntoni

    2017-08-01

    Full Text Available Space debris are orbiting objects that represent a major threat for space operations. The most used countermeasure to face this threat is, by far, collision avoidance, namely the set of maneuvers that allow to avoid a collision with the space debris. Since collision avoidance is tightly related to the knowledge of the debris state (position and speed, the observation of the orbital debris is the key of the problem. In this work a bistatic radar configuration named BIRALET (BIstatic RAdar for LEO Tracking is used to detect a set of space debris at 410 MHz, using the Sardinia Radio Telescope as the receiver antenna. The signal-to-noise ratio, the Doppler shift and the frequency spectrum for each debris are reported.

  1. Continuation from a flat to a round Earth model in the coplanar orbit transfer problem

    OpenAIRE

    Cerf, Max; Haberkorn, Thomas; Trélat, Emmanuel

    2012-01-01

    International audience; In this presentation we focus on the problem of minimization of the consumption for the coplanar orbit transfer problem. This problem is usually solved numerically by a shooting method, based on the application of the Pontryagin Maximum Principle, however the shooting method is known to be hard to initialize and the convergence is difficult to obtain due to discontinuities of the optimal control. Several tricks are known in order to overcome that problem, however in th...

  2. An LDEF 2 dust instrument for discrimination between orbital debris and natural particles in near-Earth space

    Science.gov (United States)

    Tuzzolino, A. J.; Simpson, J. A.; Mckibben, R. B.; Voss, H. D.; Gursky, H.

    1993-01-01

    The characteristics of a space dust instrument which would be ideally suited to carry out near-Earth dust measurements on a possible Long Duraction Exposure Facility reflight mission (LDEF 2) is discussed. As a model for the trajectory portion of the instrument proposed for LDEF 2, the characteristics of a SPAce DUSt instrument (SPADUS) currently under development for flight on the USA ARGOS mission to measure the flux, mass, velocity, and trajectory of near-Earth dust is summarized. Since natural (cosmic) dust and man-made dust particles (orbital debris) have different velocity and trajectory distributions, they are distinguished by means of the SPADUS velocity/trajectory information. The SPADUS measurements will cover the dust mass range approximately 5 x 10(exp -12) g (2 microns diameter) to approximately 1 x 10(exp -5) g (200 microns diameter), with an expected mean error in particle trajectory of approximately 7 deg (isotropic flux). Arrays of capture cell devices positioned behind the trajectory instrumentation would provide for Earth-based chemical and isotopic analysis of captured dust. The SPADUS measurement principles, characteristics, its role in the ARGOS mission, and its application to an LDEF 2 mission are summarized.

  3. Detection of hypervelocity dust impacts on the Earth orbiting Cluster and MMS spacecraft and problems with signal interpretation

    Science.gov (United States)

    Vaverka, Jakub; Pellinen-Wannberg, Asta; Kero, Johan; Mann, Ingrid; De Spiegeleer, Alexandre; Hamrin, Maria; Norberg, Carol; Pitkänen, Timo

    2017-04-01

    Detection of hypervelocity dust impacts on a spacecraft body by electric field instruments have been reported by several missions such as Voyager, WIND, Cassini, STEREO. The mechanism of this detection is still not completely understood and is under intensive laboratory investigation. A commonly accepted theory is based on re-collection of plasma cloud particles generated by a hypervelocity dust impact by a spacecraft surface and an electric field antenna resulting in a fast change in the potential of the spacecraft body and antenna. These changes can be detected as a short pulse measured by the electric field instrument. We present the first detection of dust impacts on the Earth-orbiting MMS and Cluster satellites. Each of the four MMS spacecraft provide probe-to-spacecraft potential measurements for their respective the six electric field antennas. This gives a unique view on signals generated by dust impacts and allow their reliable identification which is not possible for example on the Cluster spacecraft. We discuss various instrumental effects and solitary waves, commonly present in the Earth's magnetosphere, which can be easily misinterpreted as dust impacts. We show the influence of local plasma environment on dust impact detection for satellites crossing various regions of the Earth's magnetosphere where the concentration and the temperature of plasma particles change significantly.

  4. A dynamics and control algorithm for low Earth orbit precision formation flying satellites

    Science.gov (United States)

    Eyer, Jesse Koovik

    An innovative dynamics and control algorithm is developed for a dual-nanosatellite formation flying mission. The principal function of this algorithm is to use regular GPS state measurements to determine the controlled satellite's tracking error from a set of reference trajectories in the local-vertical/local-horizontal reference frame. A linear state-feedback control law---designed using a linear quadratic regulator method---calculates the optimal thrusts necessary to correct this error and communicates the thrust directions to the attitude control system and the thrust durations to the propulsion system. The control system is developed to minimize the conflicting metrics of tracking error and DeltaV requirements. To reconfigure the formation, an optimization algorithm is designed using the analytical solution to the state-space equation and the Hill-Clohessy-Wiltshire state transition matrix to solve for dual-thrust reconfiguration maneuvers. The resulting trajectories require low DeltaV, use finite-time thrusts and are accurate in a fully nonlinear orbital environment. This algorithm will be used to control the CanX-4&5 formation flying demonstration mission. In addition, an iterative method which numerically generates quasi periodic trajectories for a satellite formation is presented. This novel technique utilizes a shooting approach to the Newton method to close the relative deputy trajectory over a specific number of orbits, then fits the actual perturbed motion of the deputy with a Fourier series to enforce periodicity. This process is applied to two well-known satellite formations: a projected circular orbit and a J2-invariant formation. Compared to conventional formations, these resulting quasi-periodic trajectories require a dramatically lower control effort to maintain and could therefore be used to extend DeltaV-limited formation flying missions. Finally, an analytical study of the stability of the formation flying algorithm is conducted. To facilitate

  5. A Survey and Performance Analysis of Orbit Propagators for LEO, GEO, and Highly Elliptical Orbits

    Science.gov (United States)

    Shuster, Simon P.

    On-orbit targeting, guidance, and navigation relies on state vector propagation algorithms that must strike a balance between accuracy and computational efficiency. To better understand this balance, the relative position accuracy and computational requirements of numerical and analytical propagation methods are analyzed for a variety of orbits. For numerical propagation, several differential equation formulations (Cowell, Encke-time, Encke-beta, and Equinoctial Elements) are compared over a range of integration step sizes for a given set of perturbations and numerical integration methods. This comparison is repeated for two numerical integrators: a Runge-Kutta 4th order and a NLZD4/4. For analytical propagation, SGP4, which relies on mean orbital elements, is compared for element sets averaged with different amounts of orbit data.

  6. Frozen orbits at high eccentricity and inclination: application to Mercury orbiter

    Science.gov (United States)

    Delsate, N.; Robutel, P.; Lemaître, A.; Carletti, T.

    2010-11-01

    We hereby study the stability of a massless probe orbiting around an oblate central body (planet or planetary satellite) perturbed by a third body, assumed to lay in the equatorial plane (Sun or Jupiter for example) using a Hamiltonian formalism. We are able to determine, in the parameters space, the location of the frozen orbits, namely orbits whose orbital elements remain constant on average, to characterize their stability/unstability and to compute the periods of the equilibria. The proposed theory is general enough, to be applied to a wide range of probes around planet or natural planetary satellites. The BepiColombo mission is used to motivate our analysis and to provide specific numerical data to check our analytical results. Finally, we also bring to the light that the coefficient J 2 is able to protect against the increasing of the eccentricity due to the Kozai-Lidov effect and the coefficient J 3 determines a shift of the equilibria.

  7. Replacing critical rare earth materials in high energy density magnets

    Science.gov (United States)

    McCallum, R. William

    2012-02-01

    High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.

  8. Topology and slowing down of high energy ion orbits

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, L.G. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Porcelli, F. [Politecnico di Torino, Turin (Italy); Berk, H.L. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies

    1994-07-01

    An analysis of nonstandard guiding centre orbits is presented, which is relevant to MeV ions in a Tokamak. The orbit equation has been simplified from the start, allowing to present an analytic classification of the possible orbits. The topological transitions of the orbits during collisional slowing down are described. In particular, the characteristic equations reveal the existence of a single fixed point in the relevant phase plane, and the presence of a bifurcation curve corresponding to the locus of the pinch orbits. A significant particle inward pinch has been discovered. (authors). 7 figs.

  9. A Delphi-Based Framework for systems architecting of in-orbit exploration infrastructure for human exploration beyond Low Earth Orbit

    Science.gov (United States)

    Aliakbargolkar, Alessandro; Crawley, Edward F.

    2014-01-01

    The current debate in the U.S. Human Spaceflight Program focuses on the development of the next generation of man-rated heavy lift launch vehicles. While launch vehicle systems are of critical importance for future exploration, a comprehensive analysis of the entire exploration infrastructure is required to avoid costly pitfalls at early stages of the design process. This paper addresses this need by presenting a Delphi-Based Systems Architecting Framework for integrated architectural analysis of future in-orbit infrastructure for human space exploration beyond Low Earth Orbit. The paper is structured in two parts. The first part consists of an expert elicitation study to identify objectives for the in-space transportation infrastructure. The study was conducted between November 2011 and January 2012 with 15 senior experts involved in human spaceflight in the United States and Europe. The elicitation study included the formation of three expert panels representing exploration, science, and policy stakeholders engaged in a 3-round Delphi study. The rationale behind the Delphi approach, as imported from social science research, is discussed. Finally, a novel version of the Delphi method is presented and applied to technical decision-making and systems architecting in the context of human space exploration. The second part of the paper describes a tradespace exploration study of in-orbit infrastructure coupled with a requirements definition exercise informed by expert elicitation. The uncertainties associated with technical requirements and stakeholder goals are explicitly considered in the analysis. The outcome of the expert elicitation process portrays an integrated view of perceived stakeholder needs within the human spaceflight community. Needs are subsequently converted into requirements and coupled to the system architectures of interest to analyze the correlation between exploration, science, and policy goals. Pareto analysis is used to identify architectures

  10. Orbitally-Modulated High Energy Emission from Millisecond Pulsar Binaries

    Science.gov (United States)

    Wadiasingh, Zorawar; Kust Harding, Alice; Venter, Christo; Boettcher, Markus; Baring, Matthew G.

    2017-08-01

    Radio, optical and X-ray followup of unidentified Fermi sources has expanded the number of known galactic-field "black widow" and "redback" millisecond pulsar binaries from four to nearly 30. Several systems observed by Chandra, XMM, Suzaku, and NuSTAR exhibit double-peaked X-ray orbital modulation. This is attributed to synchrotron emission from electrons accelerated in an intrabinary shock and Doppler boosting by mildly relativistic bulk flow along the shock. It is anticipated that NICER will also detect such emission from B1957+20 and other targets. The structure of the orbital X-ray light curves depend upon the binary inclination, shock geometry, and particle acceleration distribution. In particular, the spatial variation along the shock of the underlying electron power-law index yields energy-dependence in the shape of light curves motivating future high energy phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein. We also briefly discuss stability of the shock to dynamical perturbations for redbacks and how observations of correlated X ray-optical variability may test self-regulatory stabilizing mechanisms.

  11. High grade neuroendocrine neoplasm of the antrum and orbit.

    Science.gov (United States)

    MacIntosh, Peter W; Jakobiec, Frederick A; Stagner, Anna M; Gilani, Sapideh; Fay, Aaron

    2015-01-01

    Neuroendocrine malignancies-tumors characterized by the production of dense-core secretory granules-are most often encountered in the lungs and can also be found in extrapulmonary sites. Our patient had a primary neuroendocrine tumor of the antrum with an elusive cell of origin that secondarily invaded the inferior orbit. In the sinuses, neuroendocrine tumors may be confused with infectious sinusitis or squamous cell carcinoma. There are no known pathognomonic clinical or radiographic signs to distinguish these tumors from other conditions. Diagnosis depends on a biopsy with histopathologic and immunohistochemical analysis to identify biomarkers such as synaptophysin, chromogranin, CD56 and neuron specific enolase. Our patient's tumor defied precise immunohistochemical characterization because of its primitive character and erratic biomarker expression. The diagnosis oscillated between a neuroendocrine carcinoma and an ectopic esthesioneuroblastoma grade IV-hence the use of the more generic nosologic category of neuroendocrine neoplasm without specifying a neuronal or epithelial origin. Data to guide management are limited, particularly in the ophthalmic literature, and derive from experience with tumors of the sinonasal compartments. In the present case of a sino-orbital high grade neuroendocrine neoplasm, regional lymph node metastases developed shortly after presentation. The tumor has responded well to chemotherapy and radiation, but recurrence is often encountered within 2 years in this class of neoplasms. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Role of light satellites in the high-resolution Earth observation domain

    Science.gov (United States)

    Fishman, Moshe

    1999-12-01

    Current 'classic' applications using and exploring space based earth imagery are exclusive, narrow niche tailored, expensive and hardly accessible. On the other side new, inexpensive and widely used 'consumable' applications will be only developed concurrently to the availability of appropriate imagery allowing that process. A part of these applications can be imagined today, like WWW based 'virtual tourism' or news media, but the history of technological, cultural and entertainment evolution teaches us that most of future applications are unpredictable -- they emerge together with the platforms enabling their appearance. The only thing, which can be ultimately stated, is that the definitive condition for such applications is the availability of the proper imagery platform providing low cost, high resolution, large area, quick response, simple accessibility and quick dissemination of the raw picture. This platform is a constellation of Earth Observation satellites. Up to 1995 the Space Based High Resolution Earth Observation Domain was dominated by heavy, super-expensive and very inflexible birds. The launch of Israeli OFEQ-3 Satellite by MBT Division of Israel Aircraft Industries (IAI) marked the entrance to new era of light, smart and cheap Low Earth Orbited Imaging satellites. The Earth Resource Observation System (EROS) initiated by West Indian Space, is based on OFEQ class Satellites design and it is capable to gather visual data of Earth Surface both at high resolution and large image capacity. The main attributes, derived from its compact design, low weight and sophisticated logic and which convert the EROS Satellite to valuable and productive system, are discussed. The major advantages of Light Satellites in High Resolution Earth Observation Domain are presented and WIS guidelines featuring the next generation of LEO Imaging Systems are included.

  13. Contamination Examples and Lessons from Low Earth Orbit Experiments and Operational Hardware

    Science.gov (United States)

    Pippin, Gary; Finckenor, Miria M.

    2009-01-01

    Flight experiments flown on the Space Shuttle, the International Space Station, Mir, Skylab, and free flyers such as the Long Duration Exposure Facility, the European Retrievable Carrier, and the EFFU, provide multiple opportunities for the investigation of molecular contamination effects. Retrieved hardware from the Solar Maximum Mission satellite, Mir, and the Hubble Space Telescope has also provided the means gaining insight into contamination processes. Images from the above mentioned hardware show contamination effects due to materials processing, hardware storage, pre-flight cleaning, as well as on-orbit events such as outgassing, mechanical failure of hardware in close proximity, impacts from man-made debris, and changes due to natural environment factors.. Contamination effects include significant changes to thermal and electrical properties of thermal control surfaces, optics, and power systems. Data from several flights has been used to develop a rudimentary estimate of asymptotic values for absorptance changes due to long-term solar exposure (4000-6000 Equivalent Sun Hours) of silicone-based molecular contamination deposits of varying thickness. Recommendations and suggestions for processing changes and constraints based on the on-orbit observed results will be presented.

  14. Tunable orbital angular momentum in high-harmonic generation.

    Science.gov (United States)

    Gauthier, D; Ribič, P Rebernik; Adhikary, G; Camper, A; Chappuis, C; Cucini, R; DiMauro, L F; Dovillaire, G; Frassetto, F; Géneaux, R; Miotti, P; Poletto, L; Ressel, B; Spezzani, C; Stupar, M; Ruchon, T; De Ninno, G

    2017-04-05

    Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light-matter interactions, and the disentanglement and independent control of the intrinsic and extrinsic components of the photon's angular momentum at short-wavelengths. The methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms.

  15. Analysis of Damage Probability for Collision Between Space Debris and a Satellite in Low-Earth Orbit

    Directory of Open Access Journals (Sweden)

    Jae-Eun Lee

    2007-06-01

    Full Text Available Space environment becomes more hazardous for satellite because of increasing number of space debris. This research is to analyze collision hazards between KOMPSAT 3 in low-earth orbit and space debris generated by the explosion of FengYun satellite on the January 11, 2007. Based on the observed data of the space debris from FengYun satellite, the mass and number distribution of the debris are estimated including undetectable debris from the explosion of FengYun satellite. The spatial density and flux for the space debris can be calculated according to size. This study also brings out the analysis for the assessment of collision probability and damage probability. The algorithm developed in the current paper can be used to estimate the level of risk due to space debris for the satellites that will be launched in the future.

  16. The Eccentric Behavior of Nearly Frozen Orbits

    Science.gov (United States)

    Sweetser, Theodore H.; Vincent, Mark A.

    2013-01-01

    Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

  17. Strong XUV irradiation of the Earth-sized exoplanets orbiting the ultracool dwarf TRAPPIST-1

    OpenAIRE

    Wheatley, Peter J.; Louden, Tom M.; Bourrier, Vincent; Ehrenreich, David; Gillon, Michaël

    2017-01-01

    We present an XMM-Newton X-ray observation of TRAPPIST-1, which is an ultracool dwarf star recently discovered to host three transiting and temperate Earth-sized planets. We find the star is a relatively strong and variable coronal X-ray source with an X-ray luminosity similar to that of the quiet Sun, despite its much lower bolometric luminosity.\\ud We find L_X/L_bol=2-4x10^-4, with the total XUV emission in the range L_XUV/L_bol=6-9x10^-4, \\ud and XUV irradiation of the planets that is many...

  18. The PROCESS experiment: amino and carboxylic acids under Mars-like surface UV radiation conditions in low-earth orbit.

    Science.gov (United States)

    Noblet, Audrey; Stalport, Fabien; Guan, Yuan Yong; Poch, Olivier; Coll, Patrice; Szopa, Cyril; Cloix, Mégane; Macari, Frédérique; Raulin, Francois; Chaput, Didier; Cottin, Hervé

    2012-05-01

    The search for organic molecules at the surface of Mars is a top priority of the next Mars exploration space missions: Mars Science Laboratory (NASA) and ExoMars (ESA). The detection of organic matter could provide information about the presence of a prebiotic chemistry or even biological activity on this planet. Therefore, a key step in interpretation of future data collected by these missions is to understand the preservation of organic matter in the martian environment. Several laboratory experiments have been devoted to quantifying and qualifying the evolution of organic molecules under simulated environmental conditions of Mars. However, these laboratory simulations are limited, and one major constraint is the reproduction of the UV spectrum that reaches the surface of Mars. As part of the PROCESS experiment of the European EXPOSE-E mission on board the International Space Station, a study was performed on the photodegradation of organics under filtered extraterrestrial solar electromagnetic radiation that mimics Mars-like surface UV radiation conditions. Glycine, serine, phthalic acid, phthalic acid in the presence of a mineral phase, and mellitic acid were exposed to these conditions for 1.5 years, and their evolution was determined by Fourier transform infrared spectroscopy after their retrieval. The results were compared with data from laboratory experiments. A 1.5-year exposure to Mars-like surface UV radiation conditions in space resulted in complete degradation of the organic compounds. Half-lives between 50 and 150 h for martian surface conditions were calculated from both laboratory and low-Earth orbit experiments. The results highlight that none of those organics are stable under low-Earth orbit solar UV radiation conditions.

  19. Quantum Cryptography for Secure Communications to Low-Earth Orbit Satellites

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.J.; Buttler, W.T.; Kwiat, P.G.; Lamoreaux, S.K.; Morgan, G.L.; Peterson, C.G.; Twyeffort, E.; Simmons, C.M.; Nordholt, J.E.

    1999-06-03

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. The security of these transmissions is based on the inviolability of the laws of quantum mechanics. An adversary can neither successfully tap the quantum transmissions, nor evade detection. Key material is built up using the transmission of a single-photon per bit. We have developed an experimental quantum cryptography system based on the transmission of non-orthogonal single-photon polarization states to generate shared key material over line-of-sight optical links. Our results provide strong evidence that cryptographic key material could be generated on demand between a ground station and a satellite (or between two satellites), allowing a satellite to be securely re-keyed on in orbit.

  20. Studies of Geomagnetic Pulsations Using Magnetometer Data from the CHAMP Low-Earth-Orbit Satellite and Ground-Based Stations: a Review

    Directory of Open Access Journals (Sweden)

    P R Sutcliffe

    2011-06-01

    Full Text Available We review research on geomagnetic pulsations carried out using magnetic field measurements from the CHAMP low-Earth-orbit (LEO satellite and ground-based stations in South Africa and Hungary. The high quality magnetic field measurements from CHAMP made it possible to extract and clearly resolve Pi2 and Pc3 pulsations in LEO satellite data. Our analyses for nighttime Pi2 pulsations are indicative of a cavity mode resonance. However, observations of daytime Pi2 pulsation events identified in ground station data show no convincing evidence of their occurrence in CHAMP data. We also studied low-latitude Pc3 pulsations and found that different types of field line resonant structure occur, namely discrete frequencies driven by a narrow band source and L-dependent frequencies driven by a broad band source.

  1. Comparison of high-energy trapped particle environments at the Earth and Jupiter.

    Science.gov (United States)

    Jun, Insoo; Garrett, Henry B

    2005-01-01

    The 'Van Allen belts' of the trapped energetic particles in the Earth's magnetosphere were discovered by the Explorer I satellite in 1958. In addition, in 1959, it was observed that UHF radio emissions from Jupiter probably had a similar source--the Jovian radiation belts. In this paper, the global characteristics of these two planets' trapped radiation environments and respective magnetospheres are compared and state-of-the-art models used to generate estimates of the high-energy electron (> or = 100 keV) and proton (> or = 1 MeV) populations--the dominant radiation particles in these environments. The models used are the AP8/AE8 series for the Earth and the Divine-Garrett/GIRE model for Jupiter. To illustrate the relative magnitude of radiation effects at each planet, radiation transport calculations were performed to compute the total ionising dose levels at the geosynchronous orbit for the Earth and at Europa (Jupiter's 4th largest moon) for Jupiter. The results show that the dose rates are -0.1 krad(Si) d(-1) at the geosynchronous orbit and -30 krad(Si) d((-1) at Europa for a 2.5 mm spherical shell aluminium shield--a factor of -300 between the two planets.

  2. Life Support and Habitation Systems: Crew Support and Protection for Human Exploration Missions Beyond Low Earth Orbit

    Science.gov (United States)

    Barta, Daniel J.; McQuillan, Jeffrey

    2011-01-01

    The National Aeronautics and Space Administration (NASA) has recently expanded its mission set for possible future human exploration missions. With multiple options there is interest in identifying technology needs across these missions to focus technology investments. In addition to the Moon and other destinations in cis-lunar space, other destinations including Near Earth Objects and Mars have been added for consideration. Recently, technology programs and projects have been re-organizing to better meet the Agency s strategic goals and address needs across these potential future missions. Life Support and Habitation Systems (LSHS) is one of 10 Foundational Domains as part of the National Aeronautics and Space Administration s Exploration Technology Development Program. The chief goal of LSHS is to develop and mature advanced technologies to sustain human life on missions beyond Low Earth Orbit (LEO) to increase reliability, reduce dependency on resupply and increase vehicle self-sufficiency. For long duration exploration missions, further closure of life support systems is of interest. Focus includes key technologies for atmosphere revitalization, water recovery, waste management, thermal control and crew accommodations. Other areas of focus include technologies for radiation protection, environmental monitoring and fire protection. The aim is to recover additional consumable mass, reduce requirements for power, volume, heat rejection, crew involvement, and meet exploration vehicle requirements. This paper provides a brief description of the LSHS Foundational Domain as defined for fiscal year 2011.

  3. Evaluation of geomagnetic field models using magnetometer measurements for satellite attitude determination system at low earth orbits: Case studies

    Science.gov (United States)

    Cilden-Guler, Demet; Kaymaz, Zerefsan; Hajiyev, Chingiz

    2018-01-01

    In this study, different geomagnetic field models are compared in order to study the errors resulting from the representation of magnetic fields that affect the satellite attitude system. For this purpose, we used magnetometer data from two Low Earth Orbit (LEO) spacecraft and the geomagnetic models IGRF-12 (Thébault et al., 2015) and T89 (Tsyganenko, 1989) models to study the differences between the magnetic field components, strength and the angle between the predicted and observed vector magnetic fields. The comparisons were made during geomagnetically active and quiet days to see the effects of the geomagnetic storms and sub-storms on the predicted and observed magnetic fields and angles. The angles, in turn, are used to estimate the spacecraft attitude and hence, the differences between model and observations as well as between two models become important to determine and reduce the errors associated with the models under different space environment conditions. We show that the models differ from the observations even during the geomagnetically quiet times but the associated errors during the geomagnetically active times increase. We find that the T89 model gives closer predictions to the observations, especially during active times and the errors are smaller compared to the IGRF-12 model. The magnitude of the error in the angle under both environmental conditions was found to be less than 1°. For the first time, the geomagnetic models were used to address the effects of the near Earth space environment on the satellite attitude.

  4. Optical Orbit Determination of a Geosynchronous Earth Orbit Satellite Effected by Baseline Distances between Various Ground-based Tracking Stations Ⅱ: COMS Case with Analysis of Actual Observation Data

    Directory of Open Access Journals (Sweden)

    Ju Young Son

    2015-09-01

    Full Text Available We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS, a Geostationary Earth Orbit (GEO satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO of the Korea Astronomy and Space Science Institute (KASI, Optical Wide field Patrol (OWL at KASI, and the Chungbuk National University Observatory (CNUO from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.

  5. N2 HOMO-1 orbital cross section revealed through high-order-harmonic generation

    Science.gov (United States)

    Troß, Jan; Ren, Xiaoming; Makhija, Varun; Mondal, Sudipta; Kumarappan, Vinod; Trallero-Herrero, Carlos A.

    2017-03-01

    We measure multi-orbital contributions to high harmonic generation from aligned nitrogen. We show that the change in revival structure in the cutoff harmonics has a counterpart in the angular distribution when a lower-lying orbital contributes to the harmonic yield. This angular distribution is directly observed in the laboratory without any further deconvolution. Because of the high degree of alignment we are able to distinguish angular contributions of the highest occupied molecular orbital 1 (HOMO-1) orbital from angle-dependent spectroscopic features of the HOMO. In particular, we are able to make a direct comparison with the cross section of the HOMO-1 orbital in the extreme ultraviolet region.

  6. Dynamical evolution of space debris on high-elliptical orbits near high-order resonance zones

    Science.gov (United States)

    Kuznetsov, Eduard; Zakharova, Polina

    2015-08-01

    Both analytical and numerical results are used to study high-order resonance regions in the vicinity of Molniya-type orbits. Based on data of numerical simulations, long-term orbital evolution are studied for HEO objects depending on their AMR. The Poynting-Robertson effect causes a secular decrease in the semi-major axis of a spherically symmetrical satellite. Under the Poynting-Robertson effect, objects pass through the regions of high-order resonances. The Poynting-Robertson effect and secular perturbations of the semi-major axis lead to the formation of weak stochastic trajectories.

  7. Modulation of LISA free-fall orbits due to the Earth-Moon system

    Energy Technology Data Exchange (ETDEWEB)

    Cerdonio, Massimo; Marzari, Francesco [Department of Physics, University of Padova and INFN Padova, via Marzolo 8, I-35131 Padova (Italy); De Marchi, Fabrizio [Department of Physics, University of Trento and INFN Trento, I-38100 Povo (Trento) (Italy); De Pietri, Roberto [Department of Physics, University of Parma and INFN Parma I-43100 Parma (Italy); Jetzer, Philippe [Institute of Theoretical Physics, University of Zuerich, Winterhurerstrasse 190, 8057 Zuerich (Switzerland); Mazzolo, Giulio [Max Planck Institut fuer Gravitationsphysik, Callinstrasse 38, 30167 Hannover (Germany); Ortolan, Antonello [INFN Laboratori Nazionali di Legnaro, Viale dell' Universita 35020 Legnaro (Padova) (Italy); Sereno, Mauro, E-mail: fdemarchi@science.unitn.i [Dipartimento di Fisica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2010-08-21

    We calculate the effect of the Earth-Moon (EM) system on the free-fall motion of LISA test masses. We show that the periodic gravitational pulling of the EM system induces a resonance with fundamental frequency 1 yr{sup -1} and a series of periodic perturbations with frequencies equal to integer harmonics of the synodic month ({approx_equal} 3.92 x 10{sup -7} Hz). We then evaluate the effects of these perturbations (up to the 6th harmonics) on the relative motions between each test mass couple, finding that they range between 3 mm and 10 pm for the 2nd and 6th harmonic, respectively. If we take the LISA sensitivity curve, as extrapolated down to 10{sup -6} Hz in Bender (2003 Class. Quantum Grav. 20 301-10), we obtain that a few harmonics of the EM system can be detected in the Doppler data collected by the LISA space mission. This suggests that the EM system gravitational near field could provide an additional crosscheck to the calibration of LISA, as extended to such low frequencies.

  8. High Frequency Variations of Earth Rotation Parameters from GPS and GLONASS Observations

    Science.gov (United States)

    Wei, Erhu; Jin, Shuanggen; Wan, Lihua; Liu, Wenjie; Yang, Yali; Hu, Zhenghong

    2015-01-01

    The Earth's rotation undergoes changes with the influence of geophysical factors, such as Earth's surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP) are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations) and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas) in Polar Motion (PM) and 0.5 milli-seconds (ms) in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM) and hydrological angular momentum (HAM), which needs more detailed analysis with more geophysical data in the future. PMID:25635416

  9. High frequency variations of Earth Rotation Parameters from GPS and GLONASS observations.

    Science.gov (United States)

    Wei, Erhu; Jin, Shuanggen; Wan, Lihua; Liu, Wenjie; Yang, Yali; Hu, Zhenghong

    2015-01-28

    The Earth's rotation undergoes changes with the influence of geophysical factors, such as Earth's surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP) are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations) and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas) in Polar Motion (PM) and 0.5 milli-seconds (ms) in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM) and hydrological angular momentum (HAM), which needs more detailed analysis with more geophysical data in the future.

  10. Apollo guidance, navigation and control: Guidance system operations plan for manned CM earth orbital and lunar missions using Program COLOSSUS 3. Section 3: Digital autopilots (revision 14)

    Science.gov (United States)

    1972-01-01

    Digital autopilots for the manned command module earth orbital and lunar missions using program COLOSSUS 3 are discussed. Subjects presented are: (1) reaction control system digital autopilot, (2) thrust vector control autopilot, (3) entry autopilot and mission control programs, (4) takeover of Saturn steering, and (5) coasting flight attitude maneuver routine.

  11. Exploring the challenges of habitation design for extended human presence beyond low-earth orbit: Are new requirements and processes needed?

    NARCIS (Netherlands)

    Robinson, D.K.R.; Sterenborg, Glenn; Häuplik, Sandra; Aguzzi, Manuela

    2008-01-01

    With the renewed interest in a sustained human presence beyond low-earth orbit, habitation in space, on planets and on moons is an area that requires re-evaluation in terms of mission and habitat design—there is a need for a paradigmatic move from a design focus on short-term LEO missions to that of

  12. Sampling analysis for the Earth Radiation Budget Satellite System mission based on orbital coverage and cloud variability

    Science.gov (United States)

    Harrison, E. F.; Gibson, G. G.; Minnis, P.

    1978-01-01

    The reported study represents an extension of an investigation by Harrison et al. (1976). Based on the results of sampling studies, two 98 deg inclined orbits coupled with a 56 deg inclination orbit appear to satisfy the science requirements on both regional and zonal scales. The NOAA sun-synchronous satellites in the TIROS-N series could adequately cover the high latitudes and a satellite having an inclination of 56 deg could provide sampling in the mid and low latitude areas where variations in radiation energetics are most dynamic. Attention is given to studies of time and space coverage, zonal evaluations, a regional analysis, and statistics describing the regional variations of cloud cover. A table is presented with data concerning the uncertainty of monthly mean reflected irradiance due to cloud variability for selected northern hemisphere regions.

  13. In-orbit performance of the ITOS improved attitude control system with Hall generator brushless motor and earth-splitting technique

    Science.gov (United States)

    Peacock, W. M.

    1973-01-01

    The National Aeronautics and Space Administration (NASA), launched ITOS-D with an improved attitude control system. A Hall generator brushless dc torque motor replaced the brush dc torque motor on Tiros-M and ITOS-A. Two CO2 attitude horizon sensors and one mirror replaced the four wideband horizon sensors and two mirrors on ITOS-1 and NOAA-1. Redundant pitch-control electronic boxes containing additional electronic circuitry for earth-splitting and brushless motor electronics were used. A method of generating a spacecraft earth-facing side reference for comparison to the time occurrence of the earth-splitting pulse was used to automatically correct pitch-attitude error. A single rotating flywheel, supported by a single bearing, provided gyroscopic stability and the required momentum interchange to keep one side of the satellite facing the earth. Magnetic torquing against the earth's magnetic field eliminated the requirement for expendable propellants which would limit satellite life in orbit.

  14. Incorporating Earth Science into Other High School Science Classes

    Science.gov (United States)

    Manning, C. L. B.; Holzer, M.; Colson, M.; Courtier, A. M. B.; Jacobs, B. E.

    2016-12-01

    As states begin to review their standards, some adopt or adapt the NGSS and others write their own, many basing these on the Framework for K-12 Science Education. Both the NGSS and the Frameworks have an increased emphasis on Earth Science but many high school teachers are being asked to teach these standards in traditional Biology, Chemistry and Physics courses. At the Earth Educators Rendezvous, teachers, scientists, and science education researchers worked together to find the interconnections between the sciences using the NGSS and identified ways to reference the role of Earth Sciences in the other sciences during lectures, activities and laboratory assignments. Weaving Earth and Space sciences into the other curricular areas, the teams developed relevant problems for students to solve by focusing on using current issues, media stories, and community issues. These and other lessons and units of study will be presented along with other resources used by teachers to ensure students are gaining exposure and a deeper understanding of Earth and Space Science concepts.

  15. In Situ Experimental Studies of Fundamental Degradation Processes in the Low Earth Orbit Environment

    National Research Council Canada - National Science Library

    Yang, Judith C

    2006-01-01

    ...: Remarkably homogeneous and uniform oxides form that are thicker and more ordered towards the alpha quartz structure than the oxide formed by O2 exposure, due to the high reactivity of the AO and its kinetic energy. Ge...

  16. Fuel-Optimal Altitude Maintenance of Low-Earth-Orbit Spacecrafts by Combined Direct/Indirect Optimization

    Directory of Open Access Journals (Sweden)

    Kyung-Ha Kim

    2015-12-01

    Full Text Available This work presents fuel-optimal altitude maintenance of Low-Earth-Orbit (LEO spacecrafts experiencing non-negligible air drag and J2 perturbation. A pseudospectral (direct method is first applied to roughly estimate an optimal fuel consumption strategy, which is employed as an initial guess to precisely determine itself. Based on the physical specifications of KOrea Multi-Purpose SATellite-2 (KOMPSAT-2, a Korean artificial satellite, numerical simulations show that a satellite ascends with full thrust at the early stage of the maneuver period and then descends with null thrust. While the thrust profile is presumably bang-off, it is difficult to precisely determine the switching time by using a pseudospectral method only. This is expected, since the optimal switching epoch does not coincide with one of the collocation points prescribed by the pseudospectral method, in general. As an attempt to precisely determine the switching time and the associated optimal thrust history, a shooting (indirect method is then employed with the initial guess being obtained through the pseudospectral method. This hybrid process allows the determination of the optimal fuel consumption for LEO spacecrafts and their thrust profiles efficiently and precisely.

  17. Understanding climate sensitivity to greenhouse gas concentrations and orbital forcing in the cGenie Earth System Model of Intermediate Complexity

    Science.gov (United States)

    Rochholz, Fiona; Pälike, Heiko; Paul, André

    2017-04-01

    To better understand the Earth's climate system reaction to internal climate perturbations (i.e. changes in continental configuration or greenhouse gas concentrations) and external orbital forcing, it is crucial to determine the climate sensitivity of the system to various ranges of environmental boundary conditions. We examine the climate variability in response to orbital parameters and CO2 concentration in the atmosphere, using an Earth System Model of Intermediate Complexity (cGenie). Our low-resolution experiment model design uses a simple one-continent symmetry, includes a biogeochemical cycle, an ocean circulation and a simplified atmosphere. First we run fast models with constant values for precession, eccentricity and obliquity, thus creating strongly opposing insolation conditions, that identify variations of surface air temperature across continent and ocean. We test the sensitivity of the model to orbital variations with the initiation of a marine carbon cycle and the generation of more complex continental topologies. By changing the complexity of the carbon cycle, we quantify the effect of marine carbon cycling on the surface air temperature in a simplified world. In sensitivity experiments that run with the same model setup, we observe variations in the imprint of the orbital parameters on seasonal temperature when changing the atmospheric CO2 content. At predefined latitudes, weighted averages of mean surface air temperature across the continent and the ocean are calculated and used to estimate the impact of the orbital parameters.

  18. A Simulation of the Reception of Automatic Dependent Surveillance-Broadcast Signals in Low Earth Orbit

    Directory of Open Access Journals (Sweden)

    Richard Van Der Pryt

    2015-01-01

    Full Text Available Automatic Dependent Surveillance-Broadcast (ADS-B is an air traffic surveillance technology in which aircraft transmit position and identification. The development of space-based ADS-B will allow precise control of aircraft in areas that are not covered by radar, such as oceanic regions and high latitudes. The Royal Military College of Canada has developed a spaceborne ADS-B receiver scheduled to fly on the Canadian Advanced Nanospace eXperiment-7 (CanX-7 satellite. The payload is planned to collect data over the North Atlantic region, which will then be compared to truth data provided by air traffic services. A model was created to determine power levels arriving at the satellite to provide confidence in the ADS-B receiver and antenna proposed for CanX-7. The model takes into account neutral atmosphere and ionospheric effects, aircraft-satellite geometry, and antenna radiation patterns. A simulation was run by inserting real aircraft data from the North Atlantic Track System into the model and placing the satellite at altitudes of 400, 600, and 800 km. Results of the simulation indicate that power received at the satellite, ranging between −98.5 dBm and −103 dBm for the selected altitudes, will be sufficient to successfully conduct the mission.

  19. Modeling and Monitoring South Atlantic Anomaly in Low Earth Orbit Using SSUSI Photometric Data

    Science.gov (United States)

    Romeo, G.; Schaefer, R. K.; Paxton, L. J.; Wolven, B. C.; Romeo, O.

    2016-12-01

    High energy particles in space are a source of noise for photometric instruments. By careful treatment of this noise, we can extract a great deal of information about in situ particle fluxes (Casadio and Arino, 2011, Schaefer, et al., 2016). Here we consider the analysis of data from the Defense Meteorological Satellite Program's (DMSP) Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument to examine particle fluxes (Schaefer, et al., 2016). We demonstrate that the data from the SSUSI 427 nm nadir photometer can be used to effectively monitor particle fluxes from the South Atlantic Anomaly. An accurate extraction of particle information requires an understanding of both the signal (moonglow) and the noise (> 30 MeV protons). We show how this photometer can be used to monitor the shape and flux intensity of the SAA over a solar cycle. These data show the evolution of the SAA in time and space. We also describe how data from the SSUSI scanning imaging spectrograph can be used to isolate and remove particle noise in the images obtained from this spacecraft. Thus, in cases where Spacecraft Size Weight and Power (SWaP) are tightly constrained, photometric instruments can be enlisted for dual use, providing both optical imaging and particle detection. Noise counts in the SSUSI 427 nm nadir photometer binned into 2x2 square degree bins and averaged over the year 2004. Here we see the familiar intensity pattern of the South Atlantic Anomaly.

  20. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  1. GRACE Data-based High Accuracy Global Static Earth's Gravity Field Model

    Directory of Open Access Journals (Sweden)

    CHEN Qiujie

    2016-04-01

    Full Text Available To recover the highly accurate static earth's gravity field by using GRACE satellite data is one of the hot topics in geodesy. Since linearization errors of dynamic approach quickly increase when extending satellite arc length, we established a modified dynamic approach for processing GRACE orbit and range-rate measurements in this paper, which treated orbit observations of the twin GRACE satellites as approximate values for linearization. Using the GRACE data spanning the period Jan. 2003 to Dec. 2010, containing satellite attitudes, orbits, range-rate, and non-conservative forces, we developed two global static gravity field models. One is the unconstrained solution called Tongji-Dyn01s complete to degree and order 180; the other one is the Tongji-Dyn01k model computed by using Kaula constraint. The comparisons between our models and those latest GRACE-only models (including the AIUB-GRACE03, the GGM05S, the ITSG-Grace2014k and the Tongji-GRACE01 published by different international groups, and the external validations with marine gravity anomalies from DTU13 product and height anomalies from GPS/levelling data, were performed in this study. The results demonstrate that the Tongji-Dyn01s has the same accuracy level with those of the latest GRACE-only models, while the Tongji-Dyn01k model is closer to the EIGEN6C2 than the other GRACE-only models as a whole.

  2. Probes to the Inferior Planets - A New Dawn for NEO and IEO Detection Technology Demonstration from Heliocentric Orbits Interior to the Earth's?

    Science.gov (United States)

    Grundmann, J. T.; Mottola, S.; Drentschew, M.; Drobczyk, M.; Kahle, R.; Maiwald, V.; Quantius, D.; Zabel, P.; Van Zoest, T.

    2011-11-01

    With the launch of MESSENGER and VENUS EXPRESS, a new wave of exploration of the inner solar system has begun. Noting the growing number of probes to the inner solar system, it is proposed to connect the expertise of the respective spacecraft teams and the NEO and IEO survey community to best utilize the extended cruise phases and to provide additional data return in support of pure science as well as planetary defence. Several missions to Venus and Mercury are planned to follow in this decade. Increased interest in the inferior planets is accompanied by several missions designed to study the Sun and the interplanetary medium (IPM) from a position near or in Earth orbit, such as the STEREO probes and SDO. These augment established solar observation capabilities at the Sun-Earth L1 Lagrangian point such as the SOHO spacecraft. Thus, three distinct classes of spacecraft operate or observe interior to Earth's orbit. All these spacecraft carry powerful multispectral cameras optimized for their respective primary targets. MESSENGER is scheduled to end its six-year interplanetary cruise in March 2011 to enter Mercury orbit, but a similarly extended cruise with several gravity-assists awaits the European Mercury mission BEPICOLOMBO. Unfortunately, the automatic abort of the orbit insertion manoeuvre has also left AKATSUKI (a.k.a. Venus Climate Orbiter (VCO), Planet-C) stranded in heliocentric orbit. After an unintended fly-by, the probe will catch up with Venus in approximately six years. Meanwhile, it stays mostly interior to Venus in a planet-leading orbit. In addition to the study of comets and their interaction with the IPM, observations of small bodies akin to those carried out by outer solar system probes are occasionally attempted with the equipment available. The study of structures in the interplanetary dust (IPD) cloud has been a science objective during the cruise phase of the Japanese Venus probe AKATSUKI from Earth to Venus. IPD observations in the

  3. An adaptive guidance logic for an aeroasisted orbital transfer vehicle

    Science.gov (United States)

    Hill, O.

    1984-01-01

    The Orbital Transfer Vehicle (OTV) is to be employed for the delivery of a paylod to a high earth orbit, such as a geosynchronous orbit. Subsequently, the OTV is to return to a low earth parking orbit. The present investigation is concerned with an aeroassisted OTV (AOTV) which achieves the required reduction in velocity on its return to the parking orbit through aerodynamic braking. An adaptive guidance logic is employed to control and AOTV as it passes through the earth's upper atmosphere. Attention is given to details regarding the adaptive guidance logic, and a performance evaluation. It is found that the performance of the adaptive guidance logic is satisfactory for the considered conditions.

  4. Formation Flying In Highly Elliptical Orbits Initializing the Formation

    Science.gov (United States)

    Mailhe, Laurie; Schiff, Conrad; Hughes, Steven

    2000-01-01

    In this paper several methods are examined for initializing formations in which all spacecraft start in a common elliptical orbit subsequent to separation from the launch vehicle. The tetrahedron formation used on missions such as the Magnetospheric Multiscale (MMS), Auroral Multiscale Midex (AMM), and Cluster is used as a test bed Such a formation provides full three degrees-of-freedom in the relative motion about the reference orbit and is germane to several missions. The type of maneuver strategy that can be employed depends on the specific initial conditions of each member of the formation. Single-impulse maneuvers based on a Gaussian variation-of-parameters (VOP) approach, while operationally simple and intuitively-based, work only in a limited sense for a special class of initial conditions. These 'tailored' initial conditions are characterized as having only a few of the Keplerian elements different from the reference orbit. Attempts to achieve more generic initial conditions exceed the capabilities of the single impulse VOP. For these cases, multiple-impulse implementations are always possible but are generally less intuitive than the single-impulse case. The four-impulse VOP formalism discussed by Schaub is examined but smaller delta-V costs are achieved in our test problem by optimizing a Lambert solution.

  5. ISECG Mission Scenarios and Their Role in Informing Next Steps for Human Exploration Beyond Low Earth Orbit

    Science.gov (United States)

    Culbert, Christopher J.; Mongrard, Olivier; Satoh, Naoki; Goodliff, Kandyce; Seaman, Calvin H.; Troutman, Patrick; Martin, Eric

    2011-01-01

    The International Space Exploration Coordination Group (ISECG) was established in response to The Global Exploration Strategy (GES): The Framework for Coordination developed by fourteen space agencies* and released in May 2007. This GES Framework Document recognizes that preparing for human space exploration is a stepwise process, starting with basic knowledge and culminating in a sustained human presence in deep space. ISECG has developed several optional global exploration mission scenarios enabling the phased transition from human operations in Low Earth Orbit (LEO) and utilization of the International Space Station (ISS) to human missions beyond LEO leading ultimately to human missions to cis-lunar space, the Moon, Near Earth Asteroids, Mars and its environs. Mission scenarios provide the opportunity for judging various exploration approaches in a manner consistent with agreed international goals and strategies. Each ISECG notional mission scenario reflects a series of coordinated human and robotic exploration missions over a 25-year horizon. Mission scenarios are intended to provide insights into next steps for agency investments, following on the success of the ISS. They also provide a framework for advancing the definition of Design Reference Missions (DRMs) and the concepts for capabilities contained within. Each of the human missions contained in the scenarios has been characterized by a DRM which is a top level definition of mission sequence and the capabilities needed to execute that mission. While DRMs are generally destination focused, they will comprise capabilities which are reused or evolved from capabilities used at other destinations. In this way, an evolutionary approach to developing a robust set of capabilities to sustainably explore our solar system is defined. Agencies also recognize that jointly planning for our next steps, building on the accomplishments of ISS, is important to ensuring the robustness and sustainability of any human

  6. A comparison of mutations induced by accelerated iron particles versus those induced by low earth orbit space radiation in the FEM-3 gene of Caenorhabditis elegans

    Science.gov (United States)

    Hartman, P. S.; Hlavacek, A.; Wilde, H.; Lewicki, D.; Schubert, W.; Kern, R. G.; Kazarians, G. A.; Benton, E. V.; Benton, E. R.; Nelson, G. A.

    2001-01-01

    The fem-3 gene of Caenorhabditis elegans was employed to determine the mutation frequency as well as the nature of mutations induced by low earth orbit space radiation ambient to Space Shuttle flight STS-76. Recovered mutations were compared to those induced by accelerated iron ions generated by the AGS synchrotron accelerator at Brookhaven National Laboratory. For logistical reasons, dauer larvae were prepared at TCU, transported to either Kennedy Space Center or Brookhaven National Laboratory, flown in space or irradiated, returned to TCU and screened for mutants. A total of 25 fem-3 mutants were recovered after the shuttle flight and yielded a mutation frequency of 2.1x10(-5), roughly 3.3-fold higher than the spontaneous rate of 6.3x10(-6). Four of the mutations were homozygous inviable, suggesting that they were large deletions encompassing fem-3 as well as neighboring, essential genes. Southern blot analyses revealed that one of the 25 contained a polymorphism in fem-3, further evidence that space radiation can induce deletions. While no polymorphisms were detected among the iron ion-induced mutations, three of the 15 mutants were homozygous inviable, which is in keeping with previous observations that high LET iron particles generate deficiencies. These data provide evidence, albeit indirect, that an important mutagenic component of ambient space radiation is high LET charged particles such as iron ions.

  7. High-energy charged particle bursts in the near-Earth space as earthquake precursors

    Directory of Open Access Journals (Sweden)

    S. Yu. Aleksandrin

    2003-02-01

    Full Text Available The experimental data on high-energy charged particle fluxes, obtained in various near-Earth space experiments (MIR orbital station, METEOR-3, GAMMA and SAMPEX satellites were processed and analyzed with the goal to search for particle bursts. Particle bursts have been selected in every experiment considered. It was shown that the significant part of high-energy charged particle bursts correlates with seismic activity. Moreover, the particle bursts are observed several hours before strong earthquakes; L-shells of particle bursts and corresponding earthquakes are practically the same. Some features of a seismo-magnetosphere connection model, based on the interaction of electromagnetic emission of seismic origin and radiation belt particles, were considered. Key words. Ionospheric physics (energetic particles, trapped; energetic particles, precipitating; magnetosphere-ionosphere interactions

  8. High-energy charged particle bursts in the near-Earth space as earthquake precursors

    Directory of Open Access Journals (Sweden)

    S. Yu. Aleksandrin

    Full Text Available The experimental data on high-energy charged particle fluxes, obtained in various near-Earth space experiments (MIR orbital station, METEOR-3, GAMMA and SAMPEX satellites were processed and analyzed with the goal to search for particle bursts. Particle bursts have been selected in every experiment considered. It was shown that the significant part of high-energy charged particle bursts correlates with seismic activity. Moreover, the particle bursts are observed several hours before strong earthquakes; L-shells of particle bursts and corresponding earthquakes are practically the same. Some features of a seismo-magnetosphere connection model, based on the interaction of electromagnetic emission of seismic origin and radiation belt particles, were considered.

    Key words. Ionospheric physics (energetic particles, trapped; energetic particles, precipitating; magnetosphere-ionosphere interactions

  9. Simultaneous Laser Ranging and Communication from an Earth-Based Satellite Laser Ranging Station to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Neumann, Gregory A.; McIntire, Leva; Zellar, Ronald S.; Davidson, Frederic M.; Fong, Wai H.; hide

    2013-01-01

    We report a free space laser communication experiment from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit through the on board one-way Laser Ranging (LR) receiver. Pseudo random data and sample image files were transmitted to LRO using a 4096-ary pulse position modulation (PPM) signal format. Reed-Solomon forward error correction codes were used to achieve error free data transmission at a moderate coding overhead rate. The signal fading due to the atmosphere effect was measured and the coding gain could be estimated.

  10. Overview of NASA Earth Observing Systems Terra and Aqua Moderate Resolution Imaging Spectroradiometer Instrument Calibration Algorithms and On-Orbit Performance

    Science.gov (United States)

    Xiong, Xiaoxiong; Wenny, Brian N.; Barnes, William L.

    2009-01-01

    Since launch, the Terra and Aqua moderate resolution imaging spectroradiometer (MODIS) instruments have successfully operated on-orbit for more than 9 and 6.5 years, respectively. Iv1ODIS, a key instrument for the NASA's Earth Observing System (EOS) missions, was designed to make continuous observations for studies of Earth's land, ocean, and atmospheric properties and to extend existing data records from heritage earth-observing sensors. In addition to frequent global coverage, MODIS observations are made in 36 spectral bands, covering both solar reflective and thermal emissive spectral regions. Nearly 40 data products are routinely generated from MODIS' observations and publicly distributed for a broad range of applications. Both instruments have produced an unprecedented amount of data in support of the science community. As a general reference for understanding sensor operation and calibration, and thus science data quality, we ;provide an overview of the MODIS instruments and their pre-launch calibration and characterization, and describe their on-orbit calibration algorithms and performance. On-orbit results from both Terra and Aqua MODIS radiometric, spectral, and "spatial calibration are discussed. Currently, both instruments, including their on-board calibration devices, are healthy and are expected to continue operation for several }rears to come.

  11. The effect of a strong stellar flare on the atmospheric chemistry of an earth-like planet orbiting an M dwarf.

    Science.gov (United States)

    Segura, Antígona; Walkowicz, Lucianne M; Meadows, Victoria; Kasting, James; Hawley, Suzanne

    2010-09-01

    Main sequence M stars pose an interesting problem for astrobiology: their abundance in our galaxy makes them likely targets in the hunt for habitable planets, but their strong chromospheric activity produces high-energy radiation and charged particles that may be detrimental to life. We studied the impact of the 1985 April 12 flare from the M dwarf AD Leonis (AD Leo), simulating the effects from both UV radiation and protons on the atmospheric chemistry of a hypothetical, Earth-like planet located within its habitable zone. Based on observations of solar proton events and the Neupert effect, we estimated a proton flux associated with the flare of 5.9 × 10⁸ protons cm⁻² sr⁻¹ s⁻¹ for particles with energies >10 MeV. Then we calculated the abundance of nitrogen oxides produced by the flare by scaling the production of these compounds during a large solar proton event called the Carrington event. The simulations were performed with a 1-D photochemical model coupled to a 1-D radiative/convective model. Our results indicate that the UV radiation emitted during the flare does not produce a significant change in the ozone column depth of the planet. When the action of protons is included, the ozone depletion reaches a maximum of 94% two years after the flare for a planet with no magnetic field. At the peak of the flare, the calculated UV fluxes that reach the surface, in the wavelength ranges that are damaging for life, exceed those received on Earth during less than 100 s. Therefore, flares may not present a direct hazard for life on the surface of an orbiting habitable planet. Given that AD Leo is one of the most magnetically active M dwarfs known, this conclusion should apply to planets around other M dwarfs with lower levels of chromospheric activity.

  12. Resolving multiple molecular orbitals using two-dimensional high-harmonic spectroscopy.

    Science.gov (United States)

    Yun, Hyeok; Lee, Kyung-Min; Sung, Jae Hee; Kim, Kyung Taec; Kim, Hyung Taek; Nam, Chang Hee

    2015-04-17

    High-harmonic radiation emitted from molecules in a strong laser field contains information on molecular structure and dynamics. When multiple molecular orbitals participate in high-harmonic generation, resolving the contribution of each orbital is crucial for understanding molecular dynamics and for extending high-harmonic spectroscopy to more complicated molecules. We show that two-dimensional high-harmonic spectroscopy can resolve high-harmonic radiation emitted from the two highest-occupied molecular orbitals, HOMO and HOMO-1, of aligned molecules. By the application of an orthogonally polarized two-color laser field that consists of the fundamental and its second-harmonic fields to aligned CO2 molecules, the characteristics attributed to the two orbitals are found to be separately imprinted in odd and even harmonics. Two-dimensional high-harmonic spectroscopy may open a new route to investigate ultrafast molecular dynamics during chemical processes.

  13. Optical Orbit Determination of a Geosynchronous Earth Orbit Satellite Effected by Baseline Distances between Various Ground-based Tracking Stations I: COMS simulation case

    Directory of Open Access Journals (Sweden)

    Ju Young Son

    2015-09-01

    Full Text Available To protect and manage the Korean space assets including satellites, it is important to have precise positions and orbit information of each space objects. While Korea currently lacks optical observatories dedicated to satellite tracking, the Korea Astronomy and Space Science Institute (KASI is planning to establish an optical observatory for the active generation of space information. However, due to geopolitical reasons, it is difficult to acquire an adequately sufficient number of optical satellite observatories in Korea. Against this backdrop, this study examined the possible locations for such observatories, and performed simulations to determine the differences in precision of optical orbit estimation results in relation to the relative baseline distance between observatories. To simulate more realistic conditions of optical observation, white noise was introduced to generate observation data, which was then used to investigate the effects of baseline distance between optical observatories and the simulated white noise. We generated the optical observations with white noise to simulate the actual observation, estimated the orbits with several combinations of observation data from the observatories of various baseline differences, and compared the estimated orbits to check the improvement of precision. As a result, the effect of the baseline distance in combined optical GEO satellite observation is obvious but small compared to the observation resolution limit of optical GEO observation.

  14. Cycle life evaluation of 3 Ah Li{subx}Mn{sub2}O{sub4}-based lithium-ion secondary cells for low-earth-orbit satellites. I. Full cell results.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S.; Ogawa, K.; Kumeuchi, Y.; Enomoto, S.; Uno, M.; Saito, H.; Sone, Y.; Abraham, D.; Lindbergh, G.; Chemical Sciences and Engineering Division; Royal Inst. of Tech.; Advanced Engineering Services Co., Ltd.; NEC-Tokin Corp.; Inst. of Space and Astronautical Science

    2008-01-01

    Lithium-ion batteries are a candidate for the energy storage system onboard low-earth-orbit satellites. Cycle life performance under both orbital and terrestrial conditions must be investigated in order to evaluate any inadvertent effects due to the former and the validity of the latter, with a successful comparison allowing for the extension of terrestrial experimental matrices in order to identify the effects of ageing. The orbital performance of Li{sub x}Mn{sub 2}O{sub 4}-based pouch cells onboard the microsatellite REIMEI was monitored and compared with terrestrial experiments, with the cells found to be unaffected by orbital conditions. A lifetime matrix of different cycling depths-of-discharge (DODs: 0, 20, 40%) and temperatures (25, 45 C) was undertaken with periodic reference performance tests. A decrease in both the cell end-of-discharge cycling voltage and capacity was accelerated by both higher temperatures and larger DODs. Impedance spectra measured for all ageing conditions indicated that the increase was small, manifested in a state-of-charge dependent increase of the high-frequency semi-circle and a noticeable increase in the high-frequency real axis intercept. An evaluation of the change of both the resistance and capacity of 3 Ah cells led to the development of a potential prognostic state-of-health indicator. The use of elevated temperatures to accelerate cell ageing was validated.

  15. Cycle life evaluation of 3 Ah Li{sub x}Mn{sub 2}O{sub 4}-based lithium-ion secondary cells for low-earth-orbit satellites. I. Full cell results

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Shelley; Lindbergh, Goeran [School of Chemical Science and Engineering, Department of Chemical Engineering and Technology, Teknikringen 42, Royal Institute of Technology, Stockholm SE-100 44 (Sweden); Ogawa, Keita [Advanced Engineering Services Co., Ltd., 1-6-1 Takezono, Tsukuba, Ibaraki 305-0032 (Japan); Kumeuchi, Youichi; Enomoto, Shinsuke [NEC-Tokin Corporation, 1120 Shimokuzawa, Sagamihara, Kanagawa 229-1198 (Japan); Uno, Masatoshi; Saito, Hirobumi; Sone, Yoshitsugu [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Abraham, Daniel [Chemical Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2008-12-01

    Lithium-ion batteries are a candidate for the energy storage system onboard low-earth-orbit satellites. Cycle life performance under both orbital and terrestrial conditions must be investigated in order to evaluate any inadvertent effects due to the former and the validity of the latter, with a successful comparison allowing for the extension of terrestrial experimental matrices in order to identify the effects of ageing. The orbital performance of Li{sub x}Mn{sub 2}O{sub 4}-based pouch cells onboard the microsatellite REIMEI was monitored and compared with terrestrial experiments, with the cells found to be unaffected by orbital conditions. A lifetime matrix of different cycling depths-of-discharge (DODs: 0, 20, 40%) and temperatures (25, 45 C) was undertaken with periodic reference performance tests. A decrease in both the cell end-of-discharge cycling voltage and capacity was accelerated by both higher temperatures and larger DODs. Impedance spectra measured for all ageing conditions indicated that the increase was small, manifested in a state-of-charge dependent increase of the high-frequency semi-circle and a noticeable increase in the high-frequency real axis intercept. An evaluation of the change of both the resistance and capacity of 3 Ah cells led to the development of a potential prognostic state-of-health indicator. The use of elevated temperatures to accelerate cell ageing was validated. (author)

  16. Military Space Mission Design and Analysis in a Multi-Body Environment: An Investigation of High-Altitude Orbits as Alternative Transfer Paths, Parking Orbits for Reconstitution, and Unconventional Mission Orbits

    Science.gov (United States)

    2017-03-23

    MILITARY SPACE MISSION DESIGN AND ANALYSIS IN A MULTI- BODY ENVIRONMENT: AN INVESTIGATION OF HIGH-ALTITUDE ORBITS AS ALTERNATIVE TRANSFER PATHS...subject to copyright protection in the United States. AFIT-ENY-MS-17-M-246 MILITARY SPACE MISSION DESIGN AND ANALYSIS IN A MULTI- BODY ENVIRONMENT: AN...SPACE MISSION DESIGN AND ANALYSIS IN A MULTI- BODY ENVIRONMENT: AN INVESTIGATION OF HIGH-ALTITUDE ORBITS AS ALTERNATIVE TRANSFER PATHS, PARKING ORBITS FOR

  17. High precision and convenient extension simulation platform for satellite attitude and orbit system

    Science.gov (United States)

    Cui, Hongzheng; Han, Chao; Chen, Pei; Luo, Qinqin

    2012-01-01

    In this paper, a high precision and convenient extension simulation platform for satellite attitude and orbit system is developed, to demonstrate the satellite attitude and orbit system for given space mission, and test the new underdeveloped algorithms for attitude/orbit dynamics, attitude determination, orbit navigation, and attitude/orbit control. The simulation platform is based on Matlab/Simulink software, using the technique of Simulink modeling, importing C/Fortran code in Matlab/Simulink, and embedded Matlab function, with beautiful reusability, inheritability and expansibility. The paper orderly presents the background behind the development of the platform, the platform design architecture and capability, the validity of the platform, the inheritability and expansibility of the platform, the platform implementation example for Chinese weather satellite (FY-3), and the future development for the platform.

  18. GALILEO ORBITER A MAG RDR GASPRA HIGH RES V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated high-resolution data from the Gaspra flyby in spacecraft, EME-50, RTN and Gaspra Solar Ecliptic (GaSE) coordinates....

  19. GALILEO ORBITER V MAG RDR VENUS HIGH RES V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated high-resolution data from the Venus flyby in spacecraft, VSO coordinates. These data cover the interval 1990-02-09...

  20. GALILEO ORBITER A MAG RDR IDA HIGH RES V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated high-resolution data from the Ida flyby in spacecraft, EME-50, RTN and Ida Solar Ecliptic (IaSE) coordinates. These...

  1. TRUSSELATOR - On-Orbit Fabrication of High Performance Support Structures for Solar Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TUI proposes to develop and demonstrate a process for fabricating high-performance composite truss structures on-orbit and integrating them with thin film solar cell...

  2. TRUSSELATOR - On-Orbit Fabrication of High Performance Support Structures for Solar Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Trusselator technology will enable on-orbit fabrication of support structures for high-power solar arrays and large antennas, achieving order-of-magnitude...

  3. High purity neodymium acetate from mixed rare earth carbonates

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Carlos A. da Silva; Rocha, Soraya M. Rizzo da; Vasconcellos, Mari E. de; Lobo, Raquel M.; Seneda, Jose A., E-mail: cqueiroz@ipen.b, E-mail: smrrocha@ipen.b, E-mail: mstela@ipen.b, E-mail: rmlobo@ipen.b, E-mail: jaseneda@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pedreira, Walter dos R., E-mail: walter.pedreira@fundacentro.gov.b [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Sao Paulo, SP (Brazil)

    2011-07-01

    A simple and economical chemical process for obtaining high purity neodymium acetate is discussed. The raw material in the form rare earth carbonate is produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography technique with a strong cationic resin, proper to water treatment, and without the use of retention ions was used for the fractionating of the rare earth elements (REE). In this way, it was possible to obtain 99.9% pure Nd{sub 2}O{sub 3} in yields greater than or equal 80%, with the elution of the REE using ammonium salt of ethylenediaminetetraacetic acid (EDTA) solution in pH controlled. The complex of EDTA-neodymium was transformed into neodymium oxide, which was subsequently dissolved in acetic acid to obtain the neodymium acetates. Molecular absorption spectrophotometry was used to monitor the neodymium content during the process and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the neodymium acetates. The typical neodymium acetates obtained contain the followings contaminants in {mu}g g{sup -1}: Sc(5.1); Y (0.9); La (1.0); Ce (6.1); Pr (34,4); Sm (12.8); Eu (1.1); Gd (15.4); Tb (29.3); Dy (5.2), Ho(7.4); Er (14.6); Tm (0.3); Yb (2.5); Lu (1.0). The high purity neodymium acetates obtained from this procedure have been applied, replacing the imported product, in research and development area on rare earth catalysts. (author)

  4. An optical survey for space debris on highly eccentric and inclined MEO orbits

    Science.gov (United States)

    Silha, J.; Schildknecht, T.; Hinze, A.; Flohrer, T.; Vananti, A.

    2017-01-01

    Optical surveys for space debris in high-altitude orbits have been conducted since more than ten years. Originally these efforts concentrated mainly on the geostationary region (GEO). Corresponding observation strategies, processing techniques and cataloguing approaches have been developed and successfully applied. The ESA GEO surveys, e.g., resulted in the detection of a significant population of small-size debris and later in the discovery of high area-to-mass ratio objects in GEO-like orbits. Comparably less experience (both, in terms of practical observation and strategy definition) is available for eccentric orbits that (at least partly) are in the MEO region, in particular for the Molniya-type orbits. Different survey and follow-up strategies for searching space debris objects in highly-eccentric MEO orbits, and to acquire orbits which are sufficiently accurate to catalog such objects and to maintain their orbits over longer time spans were developed. Simulations were performed to compare the performance of different survey and cataloguing strategies. Eventually, optical observations were conducted in the framework of an ESA study using ESA's Space Debris Telescope (ESASDT) the 1-m Zeiss telescope located at the Optical Ground Station (OGS) at the Teide Observatory at Tenerife, Spain. Thirteen nights of surveys of Molniya-type orbits were performed between January and August 2013. Eventually 255 surveys were performed during these thirteen nights corresponding to about 47 h of observations. In total 30 uncorrelated faint objects were discovered. On average one uncorrelated object was found every 100 min of observations. Some of these objects show a considerable brightness variation and have a high area-to-mass ratio as determined in the orbit estimation process.

  5. Orbital free ab initio simulations of liquid alkaline earth metals: from pseudopotential construction to structural and dynamic properties.

    Science.gov (United States)

    Rio, Beatriz G del; González, Luis E

    2014-11-19

    We have performed a comprehensive study of the properties of liquid Be, Ca and Ba, through the use of orbital free ab initio simulations. To this end we have developed a force-matching method to construct the necessary local pseudopotentials from standard ab initio calculations. The structural magnitudes are analyzed, including the average and local structures and the dynamic properties are studied. We find several common features, like an asymmetric second peak in the structure factor, a large amount of local structures with five-fold symmetry, a quasi-universal behaviour of the single-particle dynamic properties and a large degree of positive dispersion in the propagation of collective density fluctuations, whose damping is dictated by slow thermal relaxations and fast viscoelastic ones. Some peculiarities in the dynamic properties are however observed, like a very high sound velocity and a large violation of the Stokes-Einstein relation for Be, or an extremely high positive dispersion and a large slope in the dispersion relation of shear waves at the onset of the wavevector region where they are supported for Ba.

  6. Radiolarian abundance - A monsoon proxy responding to the Earth`s orbital forcing: Inferences on the mid-Brunhes climate shift

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.

    at approx. 400-, 126-, 95-ka due to the Earth’s orbital eccentricity, approx. 54-, 41-, and 31-ka due to axial tilt, 23-, 19-, and 17-ka due to changes in the precession of equinoxes, besides the 15-, 13- and 11-ka sub Milankovitch cycles. The spectral...

  7. TOMS/Earth-Probe Ozone (O3) Total Column 1-Orbit L2 Swath 50x50 km V008

    Data.gov (United States)

    National Aeronautics and Space Administration — Total Ozone Mapping Spectrometer (TOMS)instruments have been successfully flown in orbit aboard the Nimbus-7(Nov. 1978 - May 1993), Meteor-3 (Aug. 1991 - Dec. 1994),...

  8. Extreme Ultraviolet Fractional Orbital Angular Momentum Beams from High Harmonic Generation

    Science.gov (United States)

    Turpin, Alex; Rego, Laura; Picón, Antonio; San Román, Julio; Hernández-García, Carlos

    2017-03-01

    We investigate theoretically the generation of extreme-ultraviolet (EUV) beams carrying fractional orbital angular momentum. To this end, we drive high-order harmonic generation with infrared conical refraction (CR) beams. We show that the high-order harmonic beams emitted in the EUV/soft x-ray regime preserve the characteristic signatures of the driving beam, namely ringlike transverse intensity profile and CR-like polarization distribution. As a result, through orbital and spin angular momentum conservation, harmonic beams are emitted with fractional orbital angular momentum, and they can be synthesized into structured attosecond helical beams -or “structured attosecond light springs”- with rotating linear polarization along the azimuth. Our proposal overcomes the state of the art limitations for the generation of light beams far from the visible domain carrying non-integer orbital angular momentum and could be applied in fields such as diffraction imaging, EUV lithography, particle trapping, and super-resolution imaging.

  9. In-Orbit Performance Evaluation of a Spaceborne High Precision Fiber Optic Gyroscope.

    Science.gov (United States)

    Jin, Jing; Zhang, Ting; Kong, Linghai; Ma, Kun

    2018-01-01

    An in-orbit experiment was launched to evaluate the performance of the spaceborne high precision fiber optic gyroscopes (FOG). The three-axis in-orbit data of the FOG were analyzed using wavelet analysis method. Features of low frequency period terms and glitch noise were demonstrated. In addition, a method to extract the random noise from the in-orbit data is proposed based on the first-order difference method and the Pauta criterion. In addition, the random walk coefficient (RWC) of the FOG was calculated with the Allan variance method. Compared the ground test results, the in-orbit performance evaluation of Spaceborne High Precision Fiber Optic Gyroscope was verified.

  10. Extreme Ultraviolet Fractional Orbital Angular Momentum Beams from High Harmonic Generation.

    Science.gov (United States)

    Turpin, Alex; Rego, Laura; Picón, Antonio; San Román, Julio; Hernández-García, Carlos

    2017-03-10

    We investigate theoretically the generation of extreme-ultraviolet (EUV) beams carrying fractional orbital angular momentum. To this end, we drive high-order harmonic generation with infrared conical refraction (CR) beams. We show that the high-order harmonic beams emitted in the EUV/soft x-ray regime preserve the characteristic signatures of the driving beam, namely ringlike transverse intensity profile and CR-like polarization distribution. As a result, through orbital and spin angular momentum conservation, harmonic beams are emitted with fractional orbital angular momentum, and they can be synthesized into structured attosecond helical beams -or "structured attosecond light springs"- with rotating linear polarization along the azimuth. Our proposal overcomes the state of the art limitations for the generation of light beams far from the visible domain carrying non-integer orbital angular momentum and could be applied in fields such as diffraction imaging, EUV lithography, particle trapping, and super-resolution imaging.

  11. CERES Top-of-Atmosphere Earth Radiation Budget Climate Data Record: Accounting for in-Orbit Changes in Instrument Calibration

    Directory of Open Access Journals (Sweden)

    Norman G. Loeb

    2016-02-01

    Full Text Available The Clouds and the Earth’s Radiant Energy System (CERES project provides observations of Earth’s radiation budget using measurements from CERES instruments onboard the Terra, Aqua and Suomi National Polar-orbiting Partnership (S-NPP satellites. As the objective is to create a long-term climate data record, it is necessary to periodically reprocess the data in order to incorporate the latest calibration changes and algorithm improvements. Here, we focus on the improvements and validation of CERES Terra and Aqua radiances in Edition 4, which are used to generate higher-level climate data products. Onboard sources indicate that the total (TOT channel response to longwave (LW radiation has increased relative to the start of the missions by 0.4% to 1%. In the shortwave (SW, the sensor response change ranges from −0.4% to 0.6%. To account for in-orbit changes in SW spectral response function (SRF, direct nadir radiance comparisons between instrument pairs on the same satellite are made and an improved wavelength dependent degradation model is used to adjust the SRF of the instrument operating in a rotating azimuth plane scan mode. After applying SRF corrections independently to CERES Terra and Aqua, monthly variations amongst these instruments are highly correlated and the standard deviation in the difference of monthly anomalies is 0.2 Wm−2 for ocean and 0.3 Wm−2 for land/desert. Additionally, trends in CERES Terra and Aqua monthly anomalies are consistent to 0.21 Wm−2 per decade for ocean and 0.31 Wm−2 per decade for land/desert. In the LW, adjustments to the TOT channel SRF are made to ensure that removal of the contribution from the SW portion of the TOT channel with SW channel radiance measurements during daytime is consistent throughout the mission. Accordingly, anomalies in day–night LW difference in Edition 4 are more consistent compared to Edition 3, particularly for the Aqua land/desert case.

  12. An optimum organizational structure for a large earth-orbiting multidisciplinary space base. Ph.D. Thesis - Fla. State Univ., 1973

    Science.gov (United States)

    Ragusa, J. M.

    1975-01-01

    An optimum hypothetical organizational structure was studied for a large earth-orbiting, multidisciplinary research and applications space base manned by a crew of technologists. Because such a facility does not presently exist, in situ empirical testing was not possible. Study activity was, therefore, concerned with the identification of a desired organizational structural model rather than with the empirical testing of the model. The essential finding of this research was that a four-level project type total matrix model will optimize the efficiency and effectiveness of space base technologists.

  13. High-latitude dust in the Earth system

    Science.gov (United States)

    Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gassó, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; McKenna-Neuman, Cheryl; Mockford, Tom; Stewart, Helena; Thorsteinsson, Throstur

    2016-06-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (≥50°N and ≥40°S) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 km2 and contribute at least 80-100 Tg yr-1 of dust to the Earth system (~5% of the global dust budget); both are projected to increase under future climate change scenarios.

  14. High-latitude dust in the Earth system

    Science.gov (United States)

    Bullard, Joanna E; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; NcKenna Neuman, Cheryl; Mockford, Tom; Stewart, Helena; Thorsteinsson, Throstur

    2016-01-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (≥50°N and ≥40°S) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 km2 and contribute at least 80–100 Tg yr−1 of dust to the Earth system (~5% of the global dust budget); both are projected to increase under future climate change scenarios.

  15. A comparison of radiation shielding effectiveness of materials for highly elliptical orbits

    Science.gov (United States)

    Emmanuel, A.; Raghavan, J.; Harris, R.; Ferguson, P.

    2014-04-01

    The Canadian Space Agency (CSA) has proposed a Polar Communications and Weather (PCW) satellite mission, in conjunction with other partners. The PCW will provide essential communications and meteorological services to the Canadian Arctic, as well as space weather observations of in situ ionizing radiation along the orbit. The CSA has identified three potential Highly Elliptical Orbits (HEOs) for a PCW satellite constellation, Molniya, Modified Tundra and Triple Apogee (TAP), each having specific merits, which would directly benefit the performance/longevity of a PCW spacecraft. Radiation shielding effectiveness of various materials was studied for the three PCW orbit options to determine the feasibility of employing materials other than conventional aluminium to achieve a specified spacecraft shielding level with weight savings over aluminium. It was found that, depending on the orbit-specific radiation environment characteristics, the benefits of using polyethylene based materials is significant enough (e.g., 22% in Molniya for PE at 50 krad TID) to merit further investigation.

  16. Connecting Earth observation to high-throughput biodiversity data

    DEFF Research Database (Denmark)

    Bush, Alex; Sollmann, Rahel; Wilting, Andreas

    2017-01-01

    Understandably, given the fast pace of biodiversity loss, there is much interest in using Earth observation technology to track biodiversity, ecosystem functions and ecosystem services. However, because most biodiversity is invisible to Earth observation, indicators based on Earth observation cou...... observation data. This approach is achievable now, offering efficient and near-real-time monitoring of management impacts on biodiversity and its functions and services....

  17. AVHRR Orbital Segment = NOAA's Advanced Very High Resolution Radiometer Files: 1992 - 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Advanced Very High Resolution Radiometer (AVHRR) data set is comprised of data collected by the AVHRR sensor and held in the archives of the USGS Earth Resources...

  18. Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

    Directory of Open Access Journals (Sweden)

    J. H. C. Bosmans

    2012-04-01

    Full Text Available In this study, we use a sophisticated high-resolution atmosphere-ocean coupled climate model, EC-Earth, to investigate the effect of Mid-Holocene orbital forcing on summer monsoons on both hemispheres. During the Mid-Holocene (6 ka, there was more summer insolation on the Northern Hemisphere than today, which intensified the meridional temperature and pressure gradients. Over North Africa, monsoonal precipitation is intensified through increased landward monsoon winds and moisture advection as well as decreased moisture convergence over the oceans and more convergence over land compared to the pre-industrial simulation. Precipitation also extends further north as the ITCZ shifts northward in response to the stronger poleward gradient of insolation. This increase and poleward extent is stronger than in most previous ocean-atmosphere GCM simulations. In north-westernmost Africa, precipitation extends up to 35° N. Over tropical Africa, internal feedbacks completely overcome the direct warming effect of increased insolation. We also find a weakened African Easterly Jet. Over Asia, monsoonal precipitation during the Mid-Holocene is increased as well, but the response is different than over North-Africa. There is more convection over land at the expense of convection over the ocean, but precipitation does not extend further northward, monsoon winds over the ocean are weaker and the surrounding ocean does not provide more moisture. On the Southern Hemisphere, summer insolation and the poleward insolation gradient were weaker during the Mid-Holocene, resulting in a reduced South American monsoon through decreased monsoon winds and less convection, as well as an equatorward shift in the ITCZ. This study corroborates the findings of paleodata research as well as previous model studies, while giving a more detailed account of Mid-Holocene monsoons.

  19. Climatologies at high resolution for the earth's land surface areas

    Science.gov (United States)

    Karger, Dirk Nikolaus; Conrad, Olaf; Böhner, Jürgen; Kawohl, Tobias; Kreft, Holger; Soria-Auza, Rodrigo Wilber; Zimmermann, Niklaus E.; Linder, H. Peter; Kessler, Michael

    2017-09-01

    High-resolution information on climatic conditions is essential to many applications in environmental and ecological sciences. Here we present the CHELSA (Climatologies at high resolution for the earth's land surface areas) data of downscaled model output temperature and precipitation estimates of the ERA-Interim climatic reanalysis to a high resolution of 30 arc sec. The temperature algorithm is based on statistical downscaling of atmospheric temperatures. The precipitation algorithm incorporates orographic predictors including wind fields, valley exposition, and boundary layer height, with a subsequent bias correction. The resulting data consist of a monthly temperature and precipitation climatology for the years 1979-2013. We compare the data derived from the CHELSA algorithm with other standard gridded products and station data from the Global Historical Climate Network. We compare the performance of the new climatologies in species distribution modelling and show that we can increase the accuracy of species range predictions. We further show that CHELSA climatological data has a similar accuracy as other products for temperature, but that its predictions of precipitation patterns are better.

  20. Evolution of Cometary Dust Particles to the Orbit of the Earth: Particle Size, Shape, and Mutual Collisions

    Science.gov (United States)

    Yang, Hongu; Ishiguro, Masateru

    2018-02-01

    In this study, we numerically investigated the orbital evolution of cometary dust particles, with special consideration of the initial size–frequency distribution (SFD) and different evolutionary tracks according to the initial orbit and particle shape. We found that close encounters with planets (mostly Jupiter) are the dominating factor determining the orbital evolution of dust particles. Therefore, the lifetimes of cometary dust particles (∼250,000 yr) are shorter than the Poynting–Robertson lifetime, and only a small fraction of large cometary dust particles can be transferred into orbits with small semimajor axes. The exceptions are dust particles from 2P/Encke and, potentially, active asteroids that have little interaction with Jupiter. We also found that the effects of dust shape, mass density, and SFD were not critical in the total mass supply rate to the interplanetary dust particle (IDP) cloud complex when these quantities are confined by observations of zodiacal light brightness and SFD around the Earth’s orbit. When we incorporate a population of fluffy aggregates discovered in the Earth’s stratosphere and the coma of 67P/Churyumov–Gerasimenko within the initial ejection, the initial SFD measured at the comae of comets (67P and 81P/Wild 2) can produce the observed SFD around the Earth’s orbit. Considering the above effects, we derived the probability of mutual collisions among dust particles within the IDP cloud for the first time in a direct manner via numerical simulation and concluded that mutual collisions can mostly be ignored.

  1. MOOSE: Manned On-Orbit Servicing Equipment

    Science.gov (United States)

    Budinoff, J.; Leontsinis, N.; Lane, J.; Singh, R.; Angelone, K.; Boswell, C.; Chamberlain, I.; Concha, M.; Corrodo, M.; Custodio, O.

    The ability to service satellites has thus far been limited to low earth orbit platforms within reach of the Space Shuttle. Other orbits, such as geosynchronous orbits containing high-value spacecraft have not been attainable by a servicing vehicle. The useful life of a satellite can be extended by replacing spent propellant and damaged orbital replacement units, forestalling the need for eventual replacement. This growing need for satellite on-orbits servicing can be met by the Manned On-Orbit Servicing Equipment (MOOSE). Missions requiring orbit transfer capability, precision manipulation and maneuvering, and man-in-the-loop control can be accomplished using MOOSE. MOOSE is a flexible, reusable, single operator, aerobraking spacecraft designed to refuel, repair, and service orbiting spacecraft. MOOSE will be deployed from Space Station Freedom, (SSF), where it will be stored, resupplied, and refurbished.

  2. An accelerating high-latitude jet in Earth's core

    Science.gov (United States)

    Livermore, Phil; Hollerbach, Rainer; Finlay, Chris

    2017-04-01

    Observations of the change in Earth's magnetic field, the secular variation, provide information on the motion of liquid metal within the core that is responsible for its generation. The very latest high-resolution observations from ESA's Swarm satellite mission show intense field change at high-latitude localised in a distinctive circular daisy-chain configuration centred on the north geographic pole. Here we explain this feature with a localised, non-axisymmetric, westwards jet of 420 km width on the tangent cylinder, the cylinder of fluid within the core that is aligned with the rotation axis and tangent to the solid inner core. We find that the jet has increased in magnitude by a factor of three over the period 2000-2016 to about 40 km/yr, and is now much stronger than typical large-scale flows inferred for the core. The current accelerating phase may be a part of a longer term fluctuation of the jet causing both eastwards and westwards movement of magnetic features over historical periods, and may contribute to recent changes in torsional wave activity and the rotation direction of the inner core.

  3. Shape Shifting Satellites in Binary Near-Earth Asteroids: Do Meteoroid Impacts Play a Role in BYORP Orbital Evolution?

    Science.gov (United States)

    Rubincam, David Parry

    2012-01-01

    Less than catastrophic meteoroid impacts over 10(exp 5) years may change the shape of small rubble-pile satellites in binary NEAs, lengthening the average BYORP (binary Yarkovsky-Radzievskii-Paddack) rate of orbital evolution. An estimate of shape-shifting meteoroid fluxes give numbers close enough to causing random walks in the semimajor axis of binary systems to warrant further investigation

  4. The stability of tightly-packed, evenly-spaced systems of Earth-mass planets orbiting a Sun-like star

    Science.gov (United States)

    Obertas, Alysa; Van Laerhoven, Christa; Tamayo, Daniel

    2017-09-01

    Many of the multi-planet systems discovered to date have been notable for their compactness, with neighbouring planets closer together than any in the Solar System. Interestingly, planet-hosting stars have a wide range of ages, suggesting that such compact systems can survive for extended periods of time. We have used numerical simulations to investigate how quickly systems go unstable in relation to the spacing between planets, focusing on hypothetical systems of Earth-mass planets on evenly-spaced orbits (in mutual Hill radii). In general, the further apart the planets are initially, the longer it takes for a pair of planets to undergo a close encounter. We recover the results of previous studies, showing a linear trend in the initial planet spacing between 3 and 8 mutual Hill radii and the logarithm of the stability time. Investigating thousands of simulations with spacings up to 13 mutual Hill radii reveals distinct modulations superimposed on this relationship in the vicinity of first and second-order mean motion resonances of adjacent and next-adjacent planets. We discuss the impact of this structure and the implications on the stability of compact multi-planet systems. Applying the outcomes of our simulations, we show that isolated systems of up to five Earth-mass planets can fit in the habitable zone of a Sun-like star without close encounters for at least 109 orbits.

  5. Effect of the orbital debris environment on the high-energy Van Allen proton belt

    Science.gov (United States)

    Konradi, Andrei

    1988-01-01

    The lifetimes of high-energy (greater than 55 MeV) protons in the Van Allen radiation belt are calculated, assuming that in time the protons will collide with and be absorbed by particulate orbiting material. The calculations are based on the NASA/DoD Civil Needs Database for orbital debris (Gaines, 1966) and moderate assumptions of future space traffic. It is found that the lifetimes of high-energy protons below 1500 km will decrease, leading to a noticeable redution in their fluxes.

  6. A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e

    Science.gov (United States)

    Esteves, Lisa J.; de Mooij, Ernst J. W.; Jayawardhana, Ray; Watson, Chris; de Kok, Remco

    2017-06-01

    We present the analysis of high-resolution optical spectra of four transits of 55Cnc e, a low-density super-Earth that orbits a nearby Sun-like star in under 18 hr. The inferred bulk density of the planet implies a substantial envelope, which, according to mass-radius relationships, could be either a low-mass extended or a high-mass compact atmosphere. Our observations investigate the latter scenario, with water as the dominant species. We take advantage of the Doppler cross-correlation technique, high-spectral resolution, and the large wavelength coverage of our observations to search for the signature of thousands of optical water absorption lines. Using our observations with HDS on the Subaru telescope and ESPaDOnS on the Canada-France-Hawaii Telescope, we are able to place a 3σ lower limit of 10 g mol-1 on the mean-molecular weight of 55Cnc e’s water-rich (volume mixing ratio >10%), optically thin atmosphere, which corresponds to an atmospheric scale-height of ˜80 km. Our study marks the first high-spectral resolution search for water in a super-Earth atmosphere, and demonstrates that it is possible to recover known water-vapor absorption signals in a nearby super-Earth atmosphere, using high-resolution transit spectroscopy with current ground-based instruments.

  7. Observed currents on the earth's high-latitude magnetopause

    Science.gov (United States)

    Van Allen, J. A.; Adnan, J.

    1992-01-01

    A survey of electrical currents of the earth's magnetosphere, principally at high latitudes, as inferred from magnetic vector data acquired by the Hawkeye 1 satellite, is reported. A total of 536 candidate crossings of the magnetopause were examined. A reduced data set of 139 selected cases was analyzed in detail though solar wind dynamic pressure data were available for only 117 of these cases. Inferred values of the lineal current densities on the magnetopause are in the range 5.5 to 157.5 mA/m over a wide range of solar wind dynamic pressure from 1.17 to 16.1 nPa. The apparent normal thickness of the magnetopause current sheet ranges from 30 to 850 km with mean and median values of 185 and 158 km, respectively. It is argued that the radial rate of motion of the magnetopause is of the order of 2 km/s and hence that its true thickness is of similar magnitude. The relationship of these results to models of the geomagnetic field and to other related work is discussed.

  8. An investigation of the use of cerium and polyhedral oligomeric silsesquioxanes for the protection of polymeric epoxy compounds in the low Earth orbit environment

    Science.gov (United States)

    Piness, Jessica Miriam

    Low Earth orbit presents many hazards for composites including atomic oxygen, UV radiation, thermal cycling, micrometeoroids, and high energy protons. Atomic oxygen and vacuum ultraviolet radiation are of concern for space-bound polymeric materials as they degrade the polymers used as matrices for carbon fiber composites, which are used in satellites and space vehicles due to their high strength to weight ratios. Epoxy-amine thermosets comprise a common class of matrix due to processability and good thermal attributes. Polyhedral oligomeric silsesquioxanes (POSS) have shown the ability to reduce erosion in polyimides, polyurethanes, and other polymers when exposed to atomic oxygen. The POSS particle is composed of a SiO1.5 cage from which up to eight organic pendant groups are attached at the silicon corners of the cage. POSS reduced atomic oxygen impact on polymers by a process known as glassification wherein the organic pendants are removed from the cage upon atomic oxygen exposure and then the cage rearranges to a passive silica network. In addition, POSS shows good UV absorbance in the UVb and UVc ranges and POSS can aid dispersion of titanium dioxide in a nanocomposite. In this work, Chapter I focuses on hazards in low Earth orbit, strategies for protecting organic material in orbit, and the capabilities of POSS. Chapter II details the experimental practices used in this work. Chapter III focuses on work to induce POSS phase separation and layering at the surface of an epoxy-amine thermoset. Generally, POSS is dispersed throughout a nanocomposite, and in the process of erosion by atomic oxygen, some polymer mass loss is lost before enough POSS is exposed to begin glassification. Locating POSS at a surface of composite could possibly reduce this mass loss and the objective of this research was to investigate the formation of POSS-rich surfaces. Three POSS derivatives with different pendant groups were chosen. The POSS derivatives had a range of miscibilities

  9. Getting Out of Orbit: Water Recycling Requirements and Technology Needs for Long Duration Missions Away from Earth

    Science.gov (United States)

    Barta, Daniel J.

    2017-01-01

    Deep-space crewed missions will not have regular access to the Earth's resources or the ability to rapidly return to Earth if a system fails. As crewed missions extend farther from Earth for longer periods, habitation systems must become more self-sufficient and reliable for safe, healthy, and sustainable human exploration. For human missions to Mars, Environmental Control and Life Support Systems (ECLSS) must be able operate for up to 1,100 days with minimal spares and consumables. These missions will require capabilities to more fully recycle atmospheric gases and wastewater to substantially reduce mission costs. Even with relatively austere requirements for use, water represents one of the largest consumables by mass. Systems must be available to extract and recycle water from all sources of waste. And given that there will be no opportunity to send samples back to Earth for analysis, analytical measurements will be limited to monitoring hardware brought on board the spacecraft. The Earth Reliant phase of NASA's exploration strategy includes leveraging the International Space Station (ISS) to demonstrate advanced capabilities for a robust and reliable ECLSS. The ISS Water Recovery System (WRS) includes a Urine Processor Assembly (UPA) for distillation and recovery of water from urine and a Water Processor Assembly (WPA) to process humidity condensate and urine distillate into potable water. Possible enhancements to more fully "close the water loop" include recovery of water from waste brines and solid wastes. A possible game changer is the recovery of water from local planetary resources through use of In Situ Resource Utilization (ISRU) technologies. As part of the development and demonstration sequence, NASA intends to utilize cis-Lunar space as a Proving Ground to verify systems for deep space habitation by conducting extended duration missions to validate our readiness for Mars.

  10. Solid Earth: Introduction

    Science.gov (United States)

    Rummel, R.

    1991-10-01

    The principles of the solid Earth program are introduced. When considering the study of solid Earth from space, satellites are used as beacons, inertial references, free fall probes and carrying platforms. The phenomenon measured by these satellites and the processes which can be studied as a result of these measurements are tabulated. The NASA solid Earth program focusses on research into surface kinematics, Earth rotation, land, ice, and ocean monitoring. The ESA solid Earth program identifies as its priority the Aristoteles mission for determining the gravity and magnetic field globally, with high spatial resolution and high accuracy. The Aristoteles mission characteristics and goals are listed. The benefits of the improved gravity information that will be provided by this mission are highlighted. This information will help in the following research: geodesy, orbit mechanics, geodynamics, oceanography, climate sea level, and the atmosphere.

  11. The Lunar Orbital Prospector

    Science.gov (United States)

    Redd, Frank J.; Cantrell, James N.; McCurdy, Greg

    1992-09-01

    The establishment of lunar bases will not end the need for remote sensing of the lunar surface by orbiting platforms. Human and robotic surface exploration will necessarily be limited to some proximate distance from the support base. Near real-time, high-resolution, global characterization of the lunar surface by orbiting sensing systems will continue to be essential to the understanding of the Moon's geophysical structure and the location of exploitable minerals and deposits of raw materials. The Lunar Orbital Prospector (LOP) is an orbiting sensing platform capable of supporting a variety of modular sensing packages. Serviced by a lunar-based shuttle, the LOP will permit the exchange of instrument packages to meet evolving mission needs. The ability to recover, modify, and rotate sensing packages allows their reuse in varying combinations. Combining this flexibility with robust orbit modification capabilities and near real-time telemetry links provides considerable system responsiveness. Maintenance and modification of the LOP orbit are accomplished through use of an onboard propulsion system that burns lunar-supplied oxygen and aluminum. The relatively low performance of such a system is more than compensated for by the elimination of the need for Earth-supplied propellants. The LOP concept envisions a continuous expansion of capability through the incorporation of new instrument technologies and the addition of platforms.

  12. Ultra-High Resolution Orbit Determination of (486958) 2014 MU69: Predicting an Occultation with 1% of an Orbit

    Science.gov (United States)

    Porter, Simon Bernard; Buie, Marc W.; Spencer, John R.; Folkner, William; Parker, Alex; Zangari, Amanda Marie; Verbiscer, Anne J.; Benecchi, Susan; Stern, S. Alan; Terrell, Dirk; Soto, Alejandro; Tamblyn, Peter; Wasserman, Lawrence H.; Young, Eliot F.; New Horizons MU69 Occultation Team

    2017-10-01

    In November 2015, the NASA New Horizons spacecraft burned its thrusters to intercept the cold classical Kuiper Belt Object (486958) 2014 MU69. Then, on July 17, 2017, five small telescopes in Chubut Province, Argentina recorded a solid body occultation of MU69. Both these events required an orbital solution of unprecedented accuracy, as will the January 1, 2019 flyby of MU69 by New Horizons. This was especially difficult because there were no precoveries of MU69 prior to July 2014, it is in an extremely crowded field near the galactic core, and it is faint enough to only be reliably detected by Hubble Space Telescope’s Wide Field Camera 3 (WFC3). To accomplish this, we performed an extremely detailed analysis of 237 WFC3 images, down to the subpixel distortion level, in order to produce individual probability distribution functions (PDFs) for the position of MU69 in each WFC3 image. We registered each WFC3 image against a pre-release version of the Gaia DR2 catalog, which produced even smaller residuals than the now-released DR1. We then combined these WFC3+Gaia PDFs with a high-precision few-body numerical integrator and a Monte Carlo Markov Chain (MCMC) sampler to produce a state vector PDF for MU69 at defined epoch. Propagating those state vectors from the epoch produces an instantaneous positional cloud for MU69 at any given time. This positional cloud was then directly translated into a shadow path uncertainty cloud in order to plan the MU69 occultation campaign. We will describe this process of fully propagating errors from WFC3 images to telescope sites on the ground, and also describe refinements for future guiding of New Horizons to its encounter with MU69. We thank NASA, Hubble, Gaia, CONAE, the city of Comodoro Rivadavia, and the government of Argentina for their assistance and support of the MU69 occultation campaign.

  13. Anomalous high pressure behaviour in nanosized rare earth sesquioxides

    Energy Technology Data Exchange (ETDEWEB)

    Dilawar, Nita; Varandani, Deepak; Mehrotra, Shalini; Bandyopadhyay, Ashis K [Pressure and Vacuum Standards, National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110012 (India); Poswal, Himanshu K; Sharma, Surinder M [High Pressure Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2008-03-19

    We report Raman spectroscopic studies of the nanosized rare earth sesquioxides, namely yttrium sesquioxide (Y{sub 2}O{sub 3}), gadolinium sesquioxide (Gd{sub 2}O{sub 3}) and samarium sesquioxide (Sm{sub 2}O{sub 3}), under high pressure. The samples were characterized using x-ray diffraction, Raman spectroscopy and atomic force microscopy at atmospheric pressures. Y{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} were found to be cubic at ambient, while Sm{sub 2}O{sub 3} was found to be predominantly cubic with a small fraction of monoclinic phase. The strongest Raman peaks are observed at 379, 344 and 363 cm{sup -1}, respectively, for Y{sub 2}O{sub 3}, Sm{sub 2}O{sub 3} and Gd{sub 2}O{sub 3}. All the samples were found to be nanosized with 50-90 nm particle sizes. The high pressures were generated using a Mao-Bell type diamond anvil cell and a conventional laser Raman spectrometer is used to monitor the pressure-induced changes. Y{sub 2}O{sub 3} seems to undergo a crystalline to partial amorphous transition when pressurized up to about 19 GPa, with traces of hexagonal phase. However, on release of pressure, the hexagonal phase develops into the dominant phase. Gd{sub 2}O{sub 3} is also seen to develop into a mixture of amorphous and hexagonal phases on pressurizing. However, on release of pressure Gd{sub 2}O{sub 3} does not show any change and the transformation is found to be irreversible. On the other hand, Sm{sub 2}O{sub 3} shows a weakening of cubic phase peaks while monoclinic phase peaks gain intensity up to about a pressure of 6.79 GPa. However, thereafter the monoclinic phase peaks also reduce in intensity and mostly disordering sets in which does not show significant reversal as the pressure is released. The results obtained are discussed in detail.

  14. The Canadian Space Agency, Space Station, Strategic Technologies for Automation and Robotics Program technology development activity in protection of materials from the low Earth orbit space environment

    Science.gov (United States)

    Francoeur, J. R.

    1992-01-01

    The Strategic Technologies in Automation and Robotics (STEAR) program is managing a number of development contracts to improve the protection of spacecraft materials from the Low Earth Orbit (LEO) space environment. The project is structured in two phases over a 3 to 4 year period with a budget of 3 to 4 million dollars. Phase 1 is designed to demonstrate the technical feasibility and commercial potential of a coating/substrate system and its associated application process. The objective is to demonstrate a prototype fabrication capability using a full scale component of a commercially viable process for the protection of materials and surface finishes from the LEO space environment, and to demonstrate compliance with a set of performance requirements. Only phase 1 will be discussed in this paper.

  15. High Accuracy Ground-based near-Earth-asteroid Astrometry using Synthetic Tracking

    Science.gov (United States)

    Zhai, Chengxing; Shao, Michael; Saini, Navtej; Sandhu, Jagmit; Werne, Thomas; Choi, Philip; Ely, Todd A.; Jacobs, Chirstopher S.; Lazio, Joseph; Martin-Mur, Tomas J.; Owen, William M.; Preston, Robert; Turyshev, Slava; Michell, Adam; Nazli, Kutay; Cui, Isaac; Monchama, Rachel

    2018-01-01

    Accurate astrometry is crucial for determining the orbits of near-Earth-asteroids (NEAs). Further, the future of deep space high data rate communications is likely to be optical communications, such as the Deep Space Optical Communications package that is part of the baseline payload for the planned Psyche Discovery mission to the Psyche asteroid. We have recently upgraded our instrument on the Pomona College 1 m telescope, at JPL's Table Mountain Facility, for conducting synthetic tracking by taking many short exposure images. These images can be then combined in post-processing to track both asteroid and reference stars to yield accurate astrometry. Utilizing the precision of the current and future Gaia data releases, the JPL-Pomona College effort is now demonstrating precision astrometry on NEAs, which is likely to be of considerable value for cataloging NEAs. Further, treating NEAs as proxies of future spacecraft that carry optical communication lasers, our results serve as a measure of the astrometric accuracy that could be achieved for future plane-of-sky optical navigation.

  16. Climate of Earth-Like Planets With and Without Ocean Heat Transport Orbiting a Range of M and K Stars

    Science.gov (United States)

    Kiang, N. Y.; Jablonski, Emma R.; Way, Michael J.; Del Genio, Anthony; Roberge, Aki

    2015-01-01

    The mean surface temperature of a planet is now acknowledged as insufficient to surmise its full potential habitability. Advancing our understanding requires exploration with 3D general circulation models (GCMs), which can take into account how gradients and fluxes across a planet's surface influence the distribution of heat, clouds, and the potential for heterogeneous distribution of liquid water. Here we present 3D GCM simulations of the effects of alternative stellar spectra, instellation, model resolution, and ocean heat transport, on the simulated distribution of heat and moisture of an Earth-like planet (ELP).

  17. Characterization of the K2-18 multi-planetary system with HARPS. A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit

    Science.gov (United States)

    Cloutier, R.; Astudillo-Defru, N.; Doyon, R.; Bonfils, X.; Almenara, J.-M.; Benneke, B.; Bouchy, F.; Delfosse, X.; Ehrenreich, D.; Forveille, T.; Lovis, C.; Mayor, M.; Menou, K.; Murgas, F.; Pepe, F.; Rowe, J.; Santos, N. C.; Udry, S.; Wünsche, A.

    2017-12-01

    Aims: The bright M2.5 dwarf K2-18 (Ms = 0.36 M⊙, Rs = 0.41 R⊙) at 34 pc is known to host a transiting super-Earth-sized planet orbiting within the star's habitable zone; K2-18b. Given the superlative nature of this system for studying an exoplanetary atmosphere receiving similar levels of insolation as the Earth, we aim to characterize the planet's mass which is required to interpret atmospheric properties and infer the planet's bulk composition. Methods: We have obtained precision radial velocity measurements with the HARPS spectrograph. We then coupled those measurements with the K2 photometry to jointly model the observed radial velocity variation with planetary signals and a correlated stellar activity model based on Gaussian process regression. Results: We measured the mass of K2-18b to be 8.0 ± 1.9M⊕ with a bulk density of 3.3 ± 1.2 g/cm3 which may correspond to a predominantly rocky planet with a significant gaseous envelope or an ocean planet with a water mass fraction ≳50%. We also find strong evidence for a second, warm super-Earth K2-18c (mp,csinic = 7.5 ± 1.3 M⊕) at approximately nine days with a semi-major axis 2.4 times smaller than the transiting K2-18b. After re-analyzing the available light curves of K2-18 we conclude that K2-18c is not detected in transit and therefore likely has an orbit that is non-coplanar with the orbit of K2-18b although only a small mutual inclination is required for K2-18c to miss a transiting configuration; | Δi| 1-2°. A suite of dynamical integrations are performed to numerically confirm the system's dynamical stability. By varying the simulated orbital eccentricities of the two planets, dynamical stability constraints are used as an additional prior on each planet's eccentricity posterior from which we constrain eb < 0.43 and ec < 0.47 at the level of 99% confidence. Conclusions: The discovery of the inner planet K2-18c further emphasizes the prevalence of multi-planet systems around M dwarfs. The

  18. TWO SUPER-EARTHS ORBITING THE SOLAR ANALOG HD 41248 ON THE EDGE OF A 7:5 MEAN MOTION RESONANCE

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, J. S. [Departamento de Astronomia, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago, Casilla 36-D (Chile); Tuomi, M. [Center for Astrophysics, University of Hertfordshire, College Lane Campus, Hatfield, Hertfordshire, AL10 9AB (United Kingdom); Brasser, R. [Institute for Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan (China); Ivanyuk, O. [Main Astronomical Observatory of National Academy of Sciences of Ukraine, 27 Zabolotnoho, Kyiv 127 03680 (Ukraine); Murgas, F., E-mail: jjenkins@das.uchile.cl [Instituto de Astrofisica de Canarias, Via Lactea, E-38205 La Laguna, Tenerife (Spain)

    2013-07-01

    There are a growing number of multi-planet systems known to be orbiting their host stars with orbital periods that place them in mean motion resonances (MMRs). These systems are generally in first-order resonances and dynamical studies have focused their efforts on understanding the origin and evolution of such dynamically resonant commensurabilities. Here we report the discovery of two super-Earths that are close to a second-order dynamical resonance orbiting the metal-poor ([Fe/H] = -0.43 dex) and inactive G2V star HD 41428. We analyzed 62 HARPS archival radial velocities for this star that, until now, exhibited no evidence for planetary companions. Using our new Bayesian Doppler signal detection algorithm, we find two significant signals in the data, with periods of 18.357 days and 25.648 days, indicating they could be part of a 7:5 second-order MMR. Both semi-amplitudes are below 3 m s{sup -1} and the minimum masses of the pair are 12.3 and 8.6 M{sub Circled-Plus }, respectively. Our simulations found that apsidal alignment stabilizes the system, and even though libration of the resonant angles was not seen, the system is affected by the presence of the resonance and could still occupy the 7:5 commensurability, which would be the first planetary configuration in such a dynamical resonance. Given the multitude of low-mass multi-planet systems that will be discovered in the coming years, we expect that more of these second-order resonant configurations will emerge from the data, highlighting the need for a better understanding of the dynamical interactions between forming planetesimals.

  19. Interface between path and orbital angular momentum entanglement for high-dimensional photonic quantum information.

    Science.gov (United States)

    Fickler, Robert; Lapkiewicz, Radek; Huber, Marcus; Lavery, Martin P J; Padgett, Miles J; Zeilinger, Anton

    2014-07-30

    Photonics has become a mature field of quantum information science, where integrated optical circuits offer a way to scale the complexity of the set-up as well as the dimensionality of the quantum state. On photonic chips, paths are the natural way to encode information. To distribute those high-dimensional quantum states over large distances, transverse spatial modes, like orbital angular momentum possessing Laguerre Gauss modes, are favourable as flying information carriers. Here we demonstrate a quantum interface between these two vibrant photonic fields. We create three-dimensional path entanglement between two photons in a nonlinear crystal and use a mode sorter as the quantum interface to transfer the entanglement to the orbital angular momentum degree of freedom. Thus our results show a flexible way to create high-dimensional spatial mode entanglement. Moreover, they pave the way to implement broad complex quantum networks where high-dimensionally entangled states could be distributed over distant photonic chips.

  20. Cycle life evaluation of 3 Ah Li{sub x}Mn{sub 2}O{sub 4}-based lithium-ion secondary cells for low-earth-orbit satellites. II. Harvested electrode examination

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Shelley; Lindbergh, Goeran [School of Chemical Science and Engineering, Department of Chemical Engineering and Technology, Teknikringen 42, Royal Institute of Technology, Stockholm SE-100 44 (Sweden); Ogawa, Keita [Advanced Engineering Services Co., Ltd., 1-6-1 Takezono, Tsukuba, Ibaraki 305-0032 (Japan); Kumeuchi, Youichi; Enomoto, Shinsuke [NEC-Tokin Corporation, 1120 Shimokuzawa, Sagamihara, Kanagawa 229-1198 (Japan); Uno, Masatoshi; Saito, Hirobumi; Sone, Yoshitsugu [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Abraham, Daniel [Chemical Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2008-12-01

    Lithium-ion batteries are a candidate for the energy storage system onboard low-earth-orbit satellites. Terrestrial experiments are able to capture the performance degradation of cells in orbit, therefore providing the opportunity for lifetime investigations. The lifetime performance of 3 Ah commercial Li{sub x}Mn{sub 2}O{sub 4}-based pouch cells was evaluated in a matrix of different cycling depths-of-discharge (DODs: 0, 20, 40%) and temperatures (25, 45 C). Aged cells were disassembled and the electrochemical performance of harvested electrodes investigated with two- and three-electrode pouch cells. The positive electrode had a larger decrease in capacity than the negative electrode. Both the positive and negative electrode contributed to the increase of cell impedance measured at high states-of-charge (SOCs). The data at low SOCs indicated that the increase of cell impedance was associated with the positive electrode, which showed a significant increase in the magnitude of the high-frequency semi-circle. This SOC-dependence was observed for cells cycled for either extended periods of time or at higher temperatures with a 40% DOD swing. Low-current cycling of positive electrodes revealed a change in the second potential plateau, possibly reflecting a structural change of the Li{sub x}Mn{sub 2}O{sub 4}. This could impact on the electrode kinetics and provide a possible explanation for the SOC-dependent change of the impedance. (author)

  1. Cycle life evaluation of 3Ah Li{sub x}Mn{sub 2}O{sub 4}-based lithium-ion secondary cells for low-earth-orbit satellites. II. Harvested electrode examination.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S.; Ogawa, K.; Kumeuchi, Y.; Enomoto, S.; Uno, M.; Saito, H.; Sone, Y.; Abraham, D.; Lindbergh, G.; Chemical Sciences and Engineering Division; Royal Inst. of Tech.; Advanced Engineering Services Co.; NEC-Tokin Corp.; Inst .of Space and Astronautical Science

    2008-01-01

    Lithium-ion batteries are a candidate for the energy storage system onboard low-earth-orbit satellites. Terrestrial experiments are able to capture the performance degradation of cells in orbit, therefore providing the opportunity for lifetime investigations. The lifetime performance of 3 Ah commercial Li{sub x}Mn{sub 2}O{sub 4}-based pouch cells was evaluated in a matrix of different cycling depths-of-discharge (DODs: 0, 20, 40%) and temperatures (25, 45 C). Aged cells were disassembled and the electrochemical performance of harvested electrodes investigated with two- and three-electrode pouch cells. The positive electrode had a larger decrease in capacity than the negative electrode. Both the positive and negative electrode contributed to the increase of cell impedance measured at high states-of-charge (SOCs). The data at low SOCs indicated that the increase of cell impedance was associated with the positive electrode, which showed a significant increase in the magnitude of the high-frequency semi-circle. This SOC-dependence was observed for cells cycled for either extended periods of time or at higher temperatures with a 40% DOD swing. Low-current cycling of positive electrodes revealed a change in the second potential plateau, possibly reflecting a structural change of the Li{sub x}Mn{sub 2}O{sub 4}. This could impact on the electrode kinetics and provide a possible explanation for the SOC-dependent change of the impedance.

  2. OSSOS. V. Diffusion in the Orbit of a High-perihelion Distant Solar System Object

    Science.gov (United States)

    Bannister, Michele T.; Shankman, Cory; Volk, Kathryn; Chen, Ying-Tung; Kaib, Nathan; Gladman, Brett J.; Jakubik, Marian; Kavelaars, J. J.; Fraser, Wesley C.; Schwamb, Megan E.; Petit, Jean-Marc; Wang, Shiang-Yu; Gwyn, Stephen D. J.; Alexandersen, Mike; Pike, Rosemary E.

    2017-06-01

    We report the discovery of the minor planet 2013 SY99 on an exceptionally distant, highly eccentric orbit. With a perihelion of 50.0 au, 2013 SY99’s orbit has a semimajor axis of 730 ± 40 au, the largest known for a high-perihelion trans-Neptunian object (TNO), and well beyond those of (90377) Sedna and 2012 VP113. Yet, with an aphelion of 1420 ± 90 au, 2013 SY99’s orbit is interior to the region influenced by Galactic tides. Such TNOs are not thought to be produced in the current known planetary architecture of the solar system, and they have informed the recent debate on the existence of a distant giant planet. Photometry from the Canada-France-Hawaii Telescope, Gemini North, and Subaru indicate 2013 SY99 is ˜250 km in diameter and moderately red in color, similar to other dynamically excited TNOs. Our dynamical simulations show that Neptune’s weak influence during 2013 SY99’s perihelia encounters drives diffusion in its semimajor axis of hundreds of astronomical units over 4 Gyr. The overall symmetry of random walks in the semimajor axis allows diffusion to populate 2013 SY99’s orbital parameter space from the 1000 to 2000 au inner fringe of the Oort cloud. Diffusion affects other known TNOs on orbits with perihelia of 45 to 49 au and semimajor axes beyond 250 au. This provides a formation mechanism that implies an extended population, gently cycling into and returning from the inner fringe of the Oort cloud.

  3. Quantum Mechanical Earth: Where Orbitals Become Orbits

    Science.gov (United States)

    Keeports, David

    2012-01-01

    Macroscopic objects, although quantum mechanical by nature, conform to Newtonian mechanics under normal observation. According to the quantum mechanical correspondence principle, quantum behavior is indistinguishable from classical behavior in the limit of very large quantum numbers. The purpose of this paper is to provide an example of the…

  4. From Science Reserves to Sustainable Multiple Uses beyond Earth orbit: Evaluating Issues on the Path towards Balanced Environmental Management on Planetary Bodies

    Science.gov (United States)

    Race, Margaret

    Over the past five decades, our understanding of space beyond Earth orbit has been shaped by a succession of mainly robotic missions whose technologies have enabled scientists to answer diverse science questions about celestial bodies across the solar system. For all that time, exploration has been guided by planetary protection policies and principles promulgated by COSPAR and based on provisions in Article IX of the Outer Space Treaty of 1967. Over time, implementation of the various COSPAR planetary protection policies have sought to avoid harmful forward and backward contamination in order to ensure the integrity of science findings, guide activities on different celestial bodies, and appropriately protect Earth whenever extraterrestrial materials have been returned. The recent increased interest in extending both human missions and commercial activities beyond Earth orbit have prompted discussions in various quarters about the need for updating policies and guidelines to ensure responsible, balanced space exploration and use by all parties, regardless whether activities are undertaken by governmental or non-governmental entities. Already, numerous researchers and workgroups have suggested a range of different ways to manage activities on celestial environments (e.g, wilderness parks, exclusion zones, special regions, claims, national research bases, environmental impact assessments, etc.). While the suggestions are useful in thinking about how to manage future space activities, they are not based on any systematically applied or commonly accepted criteria (scientific or otherwise). In addition, they are borrowed from terrestrial approaches for environmental protection, which may or may not have direct applications to space environments. As noted in a recent COSPAR-PEX workshop (GWU 2012), there are no clear definitions of issues such as harmful contamination, the environment to be protected, or what are considered reasonable activity or impacts for particular

  5. Space-to-Space Power Beaming Enabling High Performance Rapid Geocentric Orbit Transfer

    Science.gov (United States)

    Dankanich, John W.; Vassallo, Corinne; Tadge, Megan

    2015-01-01

    The use of electric propulsion is more prevalent than ever, with industry pursuing all electric orbit transfers. Electric propulsion provides high mass utilization through efficient propellant transfer. However, the transfer times become detrimental as the delta V transitions from near-impulsive to low-thrust. Increasing power and therefore thrust has diminishing returns as the increasing mass of the power system limits the potential acceleration of the spacecraft. By using space-to-space power beaming, the power system can be decoupled from the spacecraft and allow significantly higher spacecraft alpha (W/kg) and therefore enable significantly higher accelerations while maintaining high performance. This project assesses the efficacy of space-to-space power beaming to enable rapid orbit transfer while maintaining high mass utilization. Concept assessment requires integrated techniques for low-thrust orbit transfer steering laws, efficient large-scale rectenna systems, and satellite constellation configuration optimization. This project includes the development of an integrated tool with implementation of IPOPT, Q-Law, and power-beaming models. The results highlight the viability of the concept, limits and paths to infusion, and comparison to state-of-the-art capabilities. The results indicate the viability of power beaming for what may be the only approach for achieving the desired transit times with high specific impulse.

  6. A solution to the problem of phaseless mapping for a high-orbit space—Ground radio interferometer

    Science.gov (United States)

    Bajkova, A. T.

    2005-12-01

    We consider the problem of mapping with ultra-high angular resolution using a space—ground radio interferometer with a space antenna in a high orbit, whose apogee height exceeds the radius of the Earth by a factor of ten. In this case, a multielement interferometer essentially degenerates into a two-element interferometer. The degeneracy of the close-phase relations prevents the use of standard methods for hybrid mapping and self-calibration for the correct reconstruction of images. We propose a new phaseless mapping method based on methods for the reconstruction of images in the complete absence of phase information, using only the amplitudes of the spatial-coherence function of the source. In connection with this problem, we propose a new method for the reliable solution of the phase problem, based on optimizing information-carrying nonlinear functionals, in particular, the Shannon entropy. Results of simulations of mapping radio sources with various structures with ultra-high angular resolution in the framework of the RADIOASTRON mission are presented.

  7. System and antenna design considerations for highly elliptical orbits as applied to the proposed Archimedes Constellation

    Science.gov (United States)

    Paynter, C.; Cuchanski, M.

    1995-01-01

    The paper discusses various aspects of the system design for a satellite in a highly elliptical inclined orbit, and presents a number of antenna design options for the proposed Archimedes mission. A satellite constellation was studied for the provision of multi media communication services in the L and S Band for northern latitudes. The inclined elliptical orbit would allow coverage of Europe, America, and East Asia. Using Canada and North America as the baseline coverage area, this paper addresses system considerations such as the satellite configuration and pointing, beam configuration, and requirements for antennas. A trade-off is performed among several antenna candidates including a direct radiating array, a focal-fed reflector, and a single reflector imaging system. Antenna geometry, performance, and beam forming methods are described. The impact of the designs on the antenna deployment is discussed.

  8. Geostationary Orbit Surveillance Using the Unscented Kalman Filter and the Analytical Orbit Model

    Directory of Open Access Journals (Sweden)

    Kyoung-Min Roh

    2011-09-01

    Full Text Available A strategy for geostationary orbit (or geostationary earth orbit [GEO] surveillance based on optical angular observations is presented in this study. For the dynamic model, precise analytical orbit model developed by Lee et al. (1997 is used to improve computation performance and the unscented Kalman filer (UKF is applied as a real-time filtering method. The UKF is known to perform well under highly nonlinear conditions such as surveillance in this study. The strategy that combines the analytical orbit propagation model and the UKF is tested for various conditions like different level of initial error and different level of measurement noise. The dependencies on observation interval and number of ground station are also tested. The test results shows that the GEO orbit determination based on the UKF and the analytical orbit model can be applied to GEO orbit tracking and surveillance effectively.

  9. A New European High Fidelity Solar Array Simulator for Near Earth and Deep Space Applications

    Directory of Open Access Journals (Sweden)

    Thorvardarson Hjalti Pall

    2017-01-01

    Full Text Available Following an intensive design, development, and testing effort of almost 3 years, Rovsing with ESA assistance succeeded in the development of a new European high fidelity Solar Array Simulator (SAS for near Earth and deep space applications. ESA now has a versatile, highly modular and efficient SAS at its disposition that serves at simulating modern high power solar arrays for Earth observation, science or telecom satellites as well as for future deep space missions.

  10. The Chocolate Shop and Atomic Orbitals: A New Atomic Model Created by High School Students to Teach Elementary Students

    Science.gov (United States)

    Liguori, Lucia

    2014-01-01

    Atomic orbital theory is a difficult subject for many high school and beginning undergraduate students, as it includes mathematical concepts not yet covered in the school curriculum. Moreover, it requires certain ability for abstraction and imagination. A new atomic orbital model "the chocolate shop" created "by" students…

  11. An interferometer for high-resolution optical surveillance from geostationary orbit

    Science.gov (United States)

    Bonino, L.; Bresciani, F.; Piasini, G.; Flebus, C.; Lecat, J.-H.; Roose, S.; Pisani, M.; Cabral, A.; Rebordão, J.; Proença, C.; Costal, J.; Lima, P. U.; Loix, N.; Musso, F.

    2017-11-01

    The activities described in this paper have been developed in the frame of the EUCLID CEPA 9 RTP 9.9 "High Resolution Optical Satellite Sensor" project of the WEAO Research Cell. They have been focused on the definition of an interferometric instrument optimised for the high-resolution optical surveillance from geostationary orbit (GEO) by means of the synthetic aperture technique, and on the definition and development of the related enabling technologies. In this paper we describe the industrial team, the selected mission specifications and overview of the whole design and manufacturing activities performed.

  12. Space Tourism: Orbital Debris Considerations

    Science.gov (United States)

    Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

    2002-01-01

    Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a

  13. Determination of the orbit of the CHAMP satellite based on the laser observations

    Science.gov (United States)

    Lejba, P.

    This work presents the results of orbit determination of the CHAMP satellite from observations of 14 the best SLR stations for year 2002 All computations were based on the Earth combined gravity field model EIGEN-CG01C Reigber et al 2005 In computations was taken the orbital programme GEODYN-II created and accesibled by NASA The got RMS value of the orbit of the CHAMP satellite is better than 30 cm The obtained results show that the orbit of the CHAMP satellite is highly perturbed by the Earth s gravity field and by the atmosphere of the Earth

  14. Relative motion of orbiting bodies

    Science.gov (United States)

    Butikov, Eugene I.

    2001-01-01

    A problem of relative motion of orbiting bodies is investigated on the example of the free motion of any body ejected from the orbital station that stays in a circular orbit around the earth. An elementary approach is illustrated by a simulation computer program and supported by a mathematical treatment based on approximate differential equations of the relative orbital motion.

  15. Combined high and low-thrust geostationary orbit insertion with radiation constraint

    Science.gov (United States)

    Macdonald, Malcolm; Owens, Steven Robert

    2018-01-01

    The sequential use of an electric propulsion system is considered in combination with a high-thrust propulsion system for application to the propellant-optimal Geostationary Orbit insertion problem, whilst considering both temporal and radiation flux constraints. Such usage is found to offer a combined propellant mass saving when compared with an equivalent high-thrust only transfer. This propellant mass saving is seen to increase as the allowable transfer duration is increased, and as the thrust from the low-thrust system is increased, assuming constant specific impulse. It was found that the required plane change maneuver is most propellant-efficiently performed by the high-thrust system. The propellant optimal trajectory incurs a significantly increased electron flux when compared to an equivalent high-thrust only transfer. However, the electron flux can be reduced to a similar order of magnitude by increasing the high-thrust propellant consumption, whilst still delivering an improved mass fraction.

  16. Thermospheric mass density measurement from precise orbit ephemeris

    OpenAIRE

    Junyu Chen; Jizhang Sang

    2016-01-01

    Atmospheric drag, which can be inferred from orbit information of low-Earth orbiting (LEO) satellites, provides a direct means of measuring mass density. The temporal resolution of derived mass density could be in the range from minutes to days, depending on the precision of the satellite orbit data. This paper presents two methods potentially being able to estimate thermosphere mass density from precise obit ephemeris with high temporal resolution. One method is based on the drag perturbatio...

  17. The use of plasma ashers and Monte Carlo modeling for the projection of atomic oxygen durability of protected polymers in low Earth orbit

    Science.gov (United States)

    Banks, Bruce A.; Auer, Bruce M.; Rutledge, Sharon K.; Degroh, Kim K.; Gebauer, Linda

    1992-01-01

    The results of ground laboratory and in-space exposure of polymeric materials to atomic oxygen has enabled the development of a Monte Carlo computational model which simulates the oxidation processes of both environments. The cost effective projection of long-term low-Earth-orbital durability of protected polymeric materials such as SiO(x)-coated polyimide Kapton photovoltaic array blankets will require ground-based testing to assure power system reliability. Although silicon dioxide thin film protective coatings can greatly extend the useful life of polymeric materials in ground-based testing, the projection of in-space durability based on these results can be made more reliable through the use of modeling which simulates the mechanistic properties of atomic oxygen interaction, and replicates test results in both environments. Techniques to project long-term performance of protected materials, such as the Space Station Freedom solar array blankets, are developed based on ground laboratory experiments, in-space experiments, and computational modeling.

  18. Electrode structure analysis and surface characterization for lithium-ion cells simulated low-Earth-orbit satellite operation. II: Electrode surface characterization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianming; Yamada, Chisa; Naito, Hitoshi; Segami, Go; Kibe, Koichi [Institute of Space Technology and Aeronautics, Japan Aerospace Exploration Agency, Tsukuba Space Center, Sengen 2-1-1, Ibaraki 305-8505 (Japan); Hironaka, Toshiya; Hayashi, Eiji; Sakiyama, Yoko; Takahashi, Yoshikazu [Toray Research Center, Inc., Sonoyama 3-3-7, Otsu, Shiga 520-8567 (Japan)

    2007-06-01

    As a sequence work to investigate the performance-degradation mechanism of an aged commercial laminated lithium-ion cell experiencing 4350-cycle charge-discharge in a simulated low-Earth-orbit (LEO) satellite operation, we performed the surface characterization of LiCoO{sub 2} cathode and graphite anode by Fourier transform infrared-Attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analysis in this work. Overall, the graphite anode had a larger change in surface chemistry than that of the LiCoO{sub 2} cathode. Except the common surface components, we detected Co metal at the aged graphite surface in the first time. This Co metal deposition was believed to originate from Co{sup 2+} dissolution from LiCoO{sub 2} cathode during prolonged cycling, and detrimental to structure stability of LiCoO{sub 2} cathode which was a main cause of cell capacity loss. The amount of surface-film component was also estimated by FTIR analysis. Though the total amount of surface film increased, the organic (inorganic) surface film decreased (increased) with prolonged cycling. (author)

  19. Electrode structure analysis and surface characterization for lithium-ion cells simulated low-Earth-orbit satellite operation. I. Electrochemical behavior and structure analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianming; Yamada, Chisa; Naito, Hitoshi; Segami, Go; Kibe, Kouichi [Institute of Space Technology and Aeronautics, Japan Aerospace Exploration Agency, Tsukuba Space Center, Sengen 2-1-1, Ibaraki 305-8505 (Japan); Sakiyama, Yoko; Takahashi, Yoshikazu; Hironaka, Toshiya; Hayashi, Eiji [Toray Research Center, Inc., Sonoyama 3-3-7, Otsu, Shiga 520-8567 (Japan)

    2007-05-01

    Lithium-ion cells for satellite applications operate under a special condition, and are expected to behave differently from those for commercial purposes. To understand the performance-degradation mechanism of lithium-ion cells experienced cycle-life testing in a simulated low-Earth-orbit (LEO) satellite operation, we conducted the structure analysis and surface characterization of the aged LiCoO{sub 2} cathode and graphite anode obtained from a lithium-ion cell with 4350-cycle LEO simulation experience. The analysis results were compared with a fresh cell which served as control. This paper provides a review of testing results on electrochemical and structure analysis. The capacity-verification and impedance measure results indicated that the LiCoO{sub 2} cathode, rather than graphite anode, was responsible for the performance degradation of the aged cell. This conclusion was confirmed by the structure analysis. The qualitative analysis of the XRD spectra disclosed that the aged cathode exhibited a much larger structure change than the aged anode. We also detected the lithium ions that were irreversibly reserved in graphite anode in XRD and {sup 7}Li nuclear magnetic resonance (NMR) analysis of aged graphite anode. These results lead us to deduce that the serious structure change in LiCoO{sub 2} cathode was primarily responsible for the performance degradation of the aged cell. (author)

  20. Reconstruction of high-dimensional states entangled in orbital angular momentum using mutually unbiased measurements

    CSIR Research Space (South Africa)

    Giovannini, D

    2013-06-01

    Full Text Available : QELS_Fundamental Science, San Jose, California United States, 9-14 June 2013 Reconstruction of High-Dimensional States Entangled in Orbital Angular Momentum Using Mutually Unbiased Measurements D. Giovannini1, ⇤, J. Romero1, 2, J. Leach3, A.... Dudley4, A. Forbes4, 5 and M. J. Padgett1 1 School of Physics and Astronomy, SUPA, University of Glasgow, Glasgow G12 8QQ, United Kingdom 2 Department of Physics, SUPA, University of Strathclyde, Glasgow G4 ONG, United Kingdom 3 School of Engineering...

  1. Elliptical polarization favors long quantum orbits in high-order above-threshold ionization of noble gases.

    Science.gov (United States)

    Lai, XuanYang; Wang, ChuanLiang; Chen, YongJu; Hu, ZiLong; Quan, Wei; Liu, XiaoJun; Chen, Jing; Cheng, Ya; Xu, ZhiZhan; Becker, Wilhelm

    2013-01-25

    We demonstrate the significant role of long quantum orbits in strong-field atomic processes by investigating experimentally and theoretically the above-threshold ionization spectra of noble gases in intense elliptically polarized laser pulses. With increasing laser ellipticity, the yields of different energy regions of the measured electron spectrum in high-order above-threshold ionization drop at different rates. The experimental features can be reproduced by a theoretical simulation based on quantum-orbit theory, revealing that increasing ellipticity favors the contributions of the long quantum orbits in the high-order above-threshold ionization process.

  2. Quantum Key Distribution with High Order Fibonacci-like Orbital Angular Momentum States

    Science.gov (United States)

    Pan, Ziwen; Cai, Jiarui; Wang, Chuan

    2017-08-01

    The coding space in quantum communication could be expanded to high-dimensional space by using orbital angular momentum (OAM) states of photons, as both the capacity of the channel and security are enhanced. Here we present a novel approach to realize high-capacity quantum key distribution (QKD) by exploiting OAM states. The innovation of the proposed approach relies on a unique type of entangled-photon source which produces entangled photons with OAM randomly distributed among high order Fiboncci-like numbers and a new physical mechanism for efficiently sharing keys. This combination of entanglement with mathematical properties of high order Fibonacci sequences provides the QKD protocol immunity to photon-number-splitting attacks and allows secure generation of long keys from few photons. Unlike other protocols, reference frame alignment and active modulation of production and detection bases are unnecessary.

  3. BioSentinel: Mission Development of a Radiation Biosensor to Gauge DNA Damage and Repair Beyond Low Earth Orbit on a 6U Nanosatellite.

    Science.gov (United States)

    Lewis, Brian; Hanel, Robert; Bhattacharya, Sharmila; Ricco, Antonion J.; Agasid, Elwood; Reiss-Bubenheim, Debra; Straume, Tore; Parra, Macerena; Boone, Travis; Santa Maria, Sergio; hide

    2015-01-01

    We are designing and developing a "6U" (10 x 22 x 34 cm; 14 kg) nanosatellite as a secondary payload to fly aboard NASA's Space Launch System (SLS) Exploration Mission (EM) 1, scheduled for launch in late 2017. For the first time in over forty years, direct experimental data from biological studies beyond low Earth orbit (LEO) will be obtained during BioSentinel's 12- to 18- month mission. BioSentinel will measure the damage and repair of DNA in a biological organism and allow us to compare that to information from onboard physical radiation sensors. In order to understand the relative contributions of the space environment's two dominant biological perturbations, reduced gravity and ionizing radiation, results from deep space will be directly compared to data obtained in LEO (on ISS) and on Earth. These data points will be available for validation of existing biological radiation damage and repair models, and for extrapolation to humans, to assist in mitigating risks during future long-term exploration missions beyond LEO. The BioSentinel Payload occupies 4U of the spacecraft and will utilize the monocellular eukaryotic organism Saccharomyces cerevisiae (yeast) to report DNA double-strand-break (DSB) events that result from ambient space radiation. DSB repair exhibits striking conservation of repair proteins from yeast to humans. Yeast was selected because of 1) its similarity to cells in higher organisms, 2) the well-established history of strains engineered to measure DSB repair, 3) its spaceflight heritage, and 4) the wealth of available ground and flight reference data. The S. cerevisiae flight strain will include engineered genetic defects to prevent growth and division until a radiation-induced DSB activates the yeast's DNA repair mechanisms. The triggered culture growth and metabolic activity directly indicate a DSB and its successful repair. The yeast will be carried in the dry state within the 1-atm P/L container in 18 separate fluidics cards with each

  4. The low Earth orbit radiation environment and its evolution from measurements using the CREAM and CREDO experiments

    Science.gov (United States)

    Dyer, C. S.; Sims, A. J.; Truscott, P. R.; Farren, J.; Underwood, C.

    1993-12-01

    The new regime of trapped protons centered around L=2.5 and observed by CRRES (Combined Release and Radiation Effects Satellite) between March and October 1991 has been observed by CREAM (Cosmic Radiation Environment and Activation Monitor) on Shuttle missions at an altitude of 569 km in September 1991 (STS-48) and at altitudes of 385 km and 326 km in December 1992 on STS-53. CREDO (Cosmic Radiation Environment and Dosimetry instrument) on UOSAT-3 at 800 km observed the decay of the belt from March 1991 to March 1992. At high latitudes cosmic-ray fluxes have increases by a factor of two between June 1991 and March 1993. The effect of Shuttle shielding on cosmic rays is to increase the fluxes of low LET (linear energy transfer) secondaries and neutrons. Trapped protons and their dose contribution are attenuated, but again significant fluxes of secondary neutrons are produced.

  5. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction

    OpenAIRE

    Cramer, Alisha J.; Cole, Jacqueline M.; Fitzgerald, Vicky; Honkimaki, Veijo; Roberts, Mark A.; Brennan, Tessa; Martin, Richard A.; Saunders, George A.; Newport, Robert J.

    2013-01-01

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3) x(R�2O3)y(P2O 5)1-(x+y), where (R, R�) denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP 5O14. Thereupon, the effects of rare-earth co-dopin...

  6. Orbital response to backward (e,e{sup `}) scattering at low and high excitation energies

    Energy Technology Data Exchange (ETDEWEB)

    Nojarov, R. [Tuebingen Univ. (Germany). Inst. fuer Theoretische Physik; Faessler, A. [Tuebingen Univ. (Germany). Inst. fuer Theoretische Physik; Dingfelder, M. [Tuebingen Univ. (Germany). Inst. fuer Theoretische Physik

    1996-04-15

    The response of orbital excitations with K{sup {pi}}=1{sup +} in heavy deformed nuclei to backward (e,e`) scattering is studied in RPA on the example of {sup 154}Sm. The summed M1 and E2 cross sections are of comparable magnitude over wide ranges of transferred momenta: 0.9high-energy region 17high-energy region. The transition densities of the single strongest RPA states from the two energy regions are similar to that of the scissors state, apart from their smaller amplitudes. The spin M1 responses are similar at low and high energy and dominant for high q. The orbital M1 response is dominant up to high q-values at low energy and only for small q at high energy. The electric response of the low RPA state (mainly C2) is suppressed at a full backward angle, while it persists at high energy for {theta}{>=}165 {sup circle} due to its dominant transverse E2 component. The E2 strength below 9 MeV and between 13 and 17 MeV belongs neither to the isoscalar nor to the isovector giant resonances. (orig.).

  7. Effects of target fragmentation on evaluation of LET spectra from space radiation in low-earth orbit (LEO) environment: impact on SEU predictions

    Science.gov (United States)

    Shinn, J. L.; Cucinotta, F. A.; Wilson, J. W.; Badhwar, G. D.; O'Neill, P. M.; Badavi, F. F.

    1995-01-01

    Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects.

  8. Major Technologies for Safe Construction of High Earth-Rockfill Dams

    Directory of Open Access Journals (Sweden)

    Hongqi Ma

    2016-12-01

    Full Text Available The earth-rockfill dam is one of the primary dam types in the selection of high dams to be constructed in Western China, since it is characterized by favorable adaptability of the dam foundation; full utilization of local earth, rock, and building-excavated materials; low construction cost; and low cement consumption. Many major technical issues regarding earth-rockfill dams with a height of over 250 m were studied and solved successfully in the construction of the 261.5 m Nuozhadu earth core rockfill dam. This paper describes research achievements and basic conclusions; systematically summarizes the accumulated experiences from the construction of the Nuozhadu Dam and other high earth-rockfill dams; and discusses major technical issues, such as deformation control, seepage control, dam slope stability, safety and control of flood discharging, safety and quality control of dam construction, safety assessments, early warning, and other key technical difficulties. This study also provides a reference and technological support for the future construction of 300 m high earth-rockfill dams.

  9. Envisioning a 21st Century, National, Spacecraft Servicing and Protection Infrastructure and Demand Potential: A Logical Development of the Earth Orbit Economy

    Science.gov (United States)

    Horsham, Gary A.

    2003-01-01

    The modern world is extremely dependent on thin strings of several hundred civil, military, and commercial spacecraft/satellites currently stationed in space. They provide a steady stream of commerce, defense, and knowledge data. This dependency will in all likelihood increase significantly during this century. A major disruption of any kind in these essential systems and networks could be socially, economically, and politically catastrophic, on a global scale. The development of a space-based, robotic services economy could be useful in mitigating this growing risk, from an efficiency and security standpoint. This paper attempts to suggest what makes sense to invest in next for the logical, economic development of Earth orbit i.e., after ISS completion. It expands on the results of an advanced market research and analysis study that sampled the opinions of several satellite industry executives and presents these results within a broad policy context. The concept of a spacecraft carrier that serves as the nucleus of a national, space-based or on-orbit, robotic services infrastructure is introduced as the next logical step for United States leadership in space. This is viewed as a reasonable and appropriate followon to the development of ELVs and satellites in the 1950s and 1960s, the Space Shuttle/PRLV in the 1970s and 1980s, and the International Space Station (ISS) in the 1980s, 1990s and 2000s. Large-scale experience in LEO-to-GEO spacecraft/satellite servicing and protection by robotic means is assumed to be an indispensable prerequisite or stepping-stone toward the development and preservation of the large scientific exploration facilities that are envisioned by NASA for operation beyond GEO. A balanced, return on national investment (RONI) strategy for space, focused on the provision of enhanced national/homeland security for increased protection, national economic/industrial expansion for increased revenue, and national scientific exploration for increased

  10. Study of high-performance canonical molecular orbitals calculation for proteins

    Science.gov (United States)

    Hirano, Toshiyuki; Sato, Fumitoshi

    2017-11-01

    The canonical molecular orbital (CMO) calculation can help to understand chemical properties and reactions in proteins. However, it is difficult to perform the CMO calculation of proteins because of its self-consistent field (SCF) convergence problem and expensive computational cost. To certainly obtain the CMO of proteins, we work in research and development of high-performance CMO applications and perform experimental studies. We have proposed the third-generation density-functional calculation method of calculating the SCF, which is more advanced than the FILE and direct method. Our method is based on Cholesky decomposition for two-electron integrals calculation and the modified grid-free method for the pure-XC term evaluation. By using the third-generation density-functional calculation method, the Coulomb, the Fock-exchange, and the pure-XC terms can be given by simple linear algebraic procedure in the SCF loop. Therefore, we can expect to get a good parallel performance in solving the SCF problem by using a well-optimized linear algebra library such as BLAS on the distributed memory parallel computers. The third-generation density-functional calculation method is implemented to our program, ProteinDF. To achieve computing electronic structure of the large molecule, not only overcoming expensive computation cost and also good initial guess for safe SCF convergence are required. In order to prepare a precise initial guess for the macromolecular system, we have developed the quasi-canonical localized orbital (QCLO) method. The QCLO has the characteristics of both localized and canonical orbital in a certain region of the molecule. We have succeeded in the CMO calculations of proteins by using the QCLO method. For simplified and semi-automated calculation of the QCLO method, we have also developed a Python-based program, QCLObot.

  11. JSC Orbital Debris Website Description

    Science.gov (United States)

    Johnson, Nicholas L.

    2006-01-01

    required. These data also help in the analysis and interpretation of impact features on returned spacecraft surfaces. 4) Mitigation - Controlling the growth of the orbital debris population is a high priority for NASA, the United States, and the major space-faring nations of the world to preserve near-Earth space for future generations. Mitigation measures can take the form of curtailing or preventing the creation of new debris, designing satellites to withstand impacts by small debris, and implementing operational procedures ranging from utilizing orbital regimes with less debris, adopting specific spacecraft attitudes, and even maneuvering to avoid collisions with debris. Downloadable items include several documents in PDF format and executable software.and 5) Reentry - Because of the increasing number of objects in space, NASA has adopted guidelines and assessment procedures to reduce the number of non-operational spacecraft and spent rocket upper stages orbiting the Earth. One method of postmission disposal is to allow reentry of these spacecraft, either from orbital decay (uncontrolled entry) or with a controlled entry. Orbital decay may be achieved by firing engines to lower the perigee altitude so that atmospheric drag will eventually cause the spacecraft to enter. However, the surviving debris impact footprint cannot be guaranteed to avoid inhabited landmasses. Controlled entry normally occurs by using a larger amount of propellant with a larger propulsion system to drive the spacecraft to enter the atmosphere at a steeper flight path angle. It will then enter at a more precise latitude, longitude, and footprint in a nearly uninhabited impact region, generally located in the ocean.

  12. NEO-LISP: Deflecting near-Earth objects using high average power, repetitively pulsed lasers

    Science.gov (United States)

    Phipps, C. R.; Michaelis, M. M.

    Several kinds of Near-Earth objects exist for which one would like to cause modest orbit perturbations, but which are inaccessible to normal means of interception because of their number, distance or the lack of early warning. For these objects, LISP (Laser Impulse Space Propulsion) is an appropriate technique for rapidly applying the required mechanical impulse from a ground-based station. In order of increasing laser energy required, examples are: (1) repositioning specially prepared geosynchronous satellites for an enhanced lifetime; (2) causing selected items of space junk to re-enter and burn up in the atmosphere on a computed trajectory; and (3) safely deflecting Earth-directed comet nuclei and earth-crossing asteroids (ECA's) a few tens of meters in size (the most hazardous size). They will discuss each of these problems in turn and show that each application is best matched by its own matrix of LISP laser pulse width, pulse repetition rate, wavelength and average power. The latter ranges from 100W to 3GW for the cases considered. They will also discuss means of achieving the active beam phase error correction during passage through the atmosphere and very large exit pupil in the optical system which are required in each of these cases.

  13. NEO-LISP: Deflecting near-earth objects using high average power, repetitively pulsed lasers

    Energy Technology Data Exchange (ETDEWEB)

    Phipps, C.R. [Los Alamos National Lab., NM (United States). Chemical Science and Technology Div.; Michaelis, M.M. [Univ. of Natal, Durban (South Africa). Physics Dept.

    1994-10-01

    Several kinds of Near-Earth objects exist for which one would like to cause modest orbit perturbations, but which are inaccessible to normal means of interception because of their number, distance or the lack of early warning. For these objects, LISP (Laser Impulse Space Propulsion) is an appropriate technique for rapidly applying the required mechanical impulse from a ground-based station. In order of increasing laser energy required, examples are: (1) repositioning specially prepared geosynchronous satellites for an enhanced lifetime, (2) causing selected items of space junk to re-enter and burn up in the atmosphere on a computed trajectory, and (3) safely deflecting Earth-directed comet nuclei and earth-crossing asteroids (ECA`s) a few tens of meters in size (the most hazardous size). They will discuss each of these problems in turn and show that each application is best matched by its own matrix of LISP laser pulse width, pulse repetition rate, wavelength and average power. The latter ranges from 100W to 3GW for the cases considered. They will also discuss means of achieving the active beam phase error correction during passage through the atmosphere and very large exit pupil in the optical system which are required in each of these cases.

  14. Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

    CERN Document Server

    Guise, Nicholas D; Tan, Joseph N

    2013-01-01

    A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning tra...

  15. Protons in near earth orbit

    CERN Document Server

    Alcaraz, J; Alpat, B; Ambrosi, G; Anderhub, H; Ao, L; Arefev, A; Azzarello, P; Babucci, E; Baldini, L; Basile, M; Barancourt, D; Barão, F; Barbier, G; Barreira, G; Battiston, R; Becker, R; Becker, U; Bellagamba, L; Béné, P; Berdugo, J; Berges, P; Bertucci, B; Biland, A; Bizzaglia, S; Blasko, S; Bölla, G; Boschini, M; Bourquin, Maurice; Bruni, G; Buénerd, M; Burger, J D; Burger, W J; Cai, X D; Cavalletti, R; Camps, C; Cannarsa, P; Capell, M; Casadei, D; Casaus, J; Castellini, G; Chang, Y H; Chen, H F; Chen, H S; Chen, Z G; Chernoplekov, N A; Chiarini, A; Tzi Hong Chiueh; Chuang, Y L; Cindolo, F; Commichau, V; Contin, A; Cotta-Ramusino, A; Crespo, P; Cristinziani, M; Da Cunha, J P; Dai, T S; Deus, J D; Dinu, N; Djambazov, L; D'Antone, I; Dong, Z R; Emonet, P; Engelberg, J; Eppling, F J; Eronen, T; Esposito, G; Extermann, Pierre; Favier, Jean; Feng, C C; Fiandrini, E; Finelli, F; Fisher, P H; Flaminio, R; Flügge, G; Fouque, N; Galaktionov, Yu; Gervasi, M; Giusti, P; Grandi, D; Gu, W Q; Hangarter, K; Hasan, A; Hermel, V; Hofer, H; Huang, M A; Hungerford, W; Ionica, M; Ionica, R; Jongmanns, M; Karlamaa, K; Karpinski, W; Kenney, G; Kenny, J; Kim, W; Klimentov, A; Kossakowski, R; Koutsenko, V F; Laborie, G; Laitinen, T; Lamanna, G; Laurenti, G; Lebedev, A; Lee, S C; Levi, G; Levchenko, P M; Liu, C L; Liu Hong Tao; Lolli, M; Lopes, I; Lu, G; Lü, Y S; Lübelsmeyer, K; Luckey, D; Lustermann, W; Maña, C; Margotti, A; Massera, F; Mayet, F; McNeil, R R; Meillon, B; Menichelli, M; Mezzanotte, F; Mezzenga, R; Mihul, A; Molinari, G; Mourão, A M; Mujunen, A; Palmonari, F; Pancaldi, G; Papi, A; Park, I H; Pauluzzi, M; Pauss, Felicitas; Perrin, E; Pesci, A; Pevsner, A; Pilastrini, R; Pimenta, M; Plyaskin, V; Pozhidaev, V; Postema, H; Postolache, V; Prati, E; Produit, N; Rancoita, P G; Rapin, D; Raupach, F; Recupero, S; Ren, D; Ren, Z; Ribordy, M; Richeux, J P; Riihonen, E; Ritakari, J; Röser, U; Roissin, C; Sagdeev, R; Santos, D; Sartorelli, G; Schultz von Dratzig, A; Schwering, G; Seo, E S; Shoutko, V; Shoumilov, E; Siedling, R; Son, D; Song, T; Steuer, M; Sun, G S; Suter, H; Tang, X W; Ting, Samuel C C; Ting, S M; Tornikoski, M; Torromeo, G; Torsti, J; Trümper, J E; Ulbricht, J; Urpo, S; Usoskin, I; Valtonen, E; Van den Hirtz, J; Velcea, F; Velikhov, E P; Verlaat, B; Vetlitskii, I; Vezzu, F; Vialle, J P; Viertel, Gert M; Vitè, Davide F; Von Gunten, H P; Waldmeier-Wicki, S; Wallraff, W; Wang, B C; Wang, J Z; Wang, Y H; Wiik, K; Williams, C; Wu, S X; Xia, P C; Yan, J L; Yan Lu Guang; Yang, C G; Yang, M; Ye Shu Wei; Yeh, P; Xu, Z Z; Zhang, H Y; Zhang, Z P; Zhao, D X; Zhu, G Y; Zhu, W Z; Zhuang, H L; Zichichi, A

    2000-01-01

    The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measuredby the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 atan altitude of 380 km. Above the geomagnetic cutoff the observed spectrum isparameterized by a power law. Below the geomagnetic cutoff a substantial secondspectrum was observed concentrated at equatorial latitudes with a flux ~ 70m^-2 sec^-1 sr^-1. Most of these second spectrum protons follow a complicatedtrajectory and originate from a restricted geographic region.

  16. Spin-orbital nature of the high-field magnetic state in the Sr4Ru3O10

    Science.gov (United States)

    Granata, Veronica; Capogna, Lucia; Forte, Filomena; Lepetit, Marie-Bernadette; Fittipaldi, Rosalba; Stunault, Anne; Cuoco, Mario; Vecchione, Antonio

    2016-03-01

    We perform a spin-polarized neutron-diffraction study to investigate the nature of the high-field magnetic state of the trilayered Sr4Ru3O10 . The analysis indicates that a high field applied within the a b plane leads to an unbalance of the spin and orbital moments with a spatial profile that is strongly tied to the layers where the electrons are located in the unit cell. We provide evidence of a layer dependent magnetic anisotropy with the inner layers having larger spin and orbital magnetic moments than the outer ones and show that such behavior is robust to temperature variation being persistent above the Curie temperature. By means of an effective model that includes the coupling between the spin-orbital degrees of freedom at inequivalent Ru sites we ascribe the origin of the layer anisotropy to the cooperative effects between octahedral distortions, spin orbit, and Coulomb interactions.

  17. Manifestations of the rotation and gravity of the Earth in high-energy physics experiments

    Science.gov (United States)

    Obukhov, Yuri N.; Silenko, Alexander J.; Teryaev, Oleg V.

    2016-08-01

    The inertial (due to rotation) and gravitational fields of the Earth affect the motion of an elementary particle and its spin dynamics. This influence is not negligible and should be taken into account in high-energy physics experiments. Earth's influence is manifest in perturbations in the particle motion, in an additional precession of the spin, and in a change of the constitutive tensor of the Maxwell electrodynamics. Bigger corrections are oscillatory, and their contributions average to zero. Other corrections due to the inhomogeneity of the inertial field are not oscillatory but they are very small and may be important only for the storage ring electric dipole moment experiments. Earth's gravity causes the Newton-like force, the reaction force provided by a focusing system, and additional torques acting on the spin. However, there are no observable indications of the electromagnetic effects due to Earth's gravity.

  18. Automatic orbital GTAW welding: Highest quality welds for tomorrow's high-performance systems

    Science.gov (United States)

    Henon, B. K.

    1985-01-01

    Automatic orbital gas tungsten arc welding (GTAW) or TIG welding is certain to play an increasingly prominent role in tomorrow's technology. The welds are of the highest quality and the repeatability of automatic weldings is vastly superior to that of manual welding. Since less heat is applied to the weld during automatic welding than manual welding, there is less change in the metallurgical properties of the parent material. The possibility of accurate control and the cleanliness of the automatic GTAW welding process make it highly suitable to the welding of the more exotic and expensive materials which are now widely used in the aerospace and hydrospace industries. Titanium, stainless steel, Inconel, and Incoloy, as well as, aluminum can all be welded to the highest quality specifications automatically. Automatic orbital GTAW equipment is available for the fusion butt welding of tube-to-tube, as well as, tube to autobuttweld fittings. The same equipment can also be used for the fusion butt welding of up to 6 inch pipe with a wall thickness of up to 0.154 inches.

  19. Hyperresolution: an hyperspectral and high resolution imager for Earth observation

    Science.gov (United States)

    De Vidi, R.; Chiarantini, L.; Bini, A.

    2017-11-01

    Hyperspectral space imagery is an emerging technology that supports many scientific, civil, security and defence operational applications. The main advantage of this remote sensing technique is that it allows the so-called Feature Extraction: in fact the spectral signature allows the recognition of the materials composing the scene. Hyperspectral Products and their applications have been investigated in the past years by Galileo Avionica to direct the instrument characteristics design. Sample products have been identified in the civil / environment monitoring fields (such as coastal monitoring, vegetation, hot spot and urban classification) and in defense / security applications: their performances have been verified by means of airborne flight campaigns. The Hyperspectral and High Resolution Imager is a space-borne instrument that implement a pushbroom technique to get strip spectral images over the Hyperspectral VNIR and SWIR bands, with a ground sample distance at nadir of 20m in a 20 km wide ground swath, with 200 spectral channels, realizing an average spectral resolution of 10nm. The High Resolution Panchromatic Channel insists in the same swath to allow for multiresolution data fusion of hyperspectral imagery.

  20. Spacecraft Orbit Determination with B Spline Approximation Method

    Science.gov (United States)

    Song, Y. Z.; Huang, Y.; Hu, X. G.; Li, P. J.; Cao, J. F.

    2013-07-01

    It is known that the dynamical orbit determination is the most common way to get the precise orbit of spacecraft. However, it is hard to describe the precise orbit of spacecraft sometimes. In order to solve this problem, the technique of the orbit determination with the B spline approximation method based on the theory of function approximation is presented in this article. Several simulation cases of the orbit determination including LEO (Low Earth Orbit), MEO (Medium Earth Orbit), and HEO (Highly Eccentric Orbit) satellites are performed, and it is shown that the accuracy of this method is reliable and stable.The approach can be performed in the conventional celestial coordinate system and conventional terrestrial coordinate system.The spacecraft's position and velocity can be calculated directly with the B spline approximation method, which means that it is unnecessary to integrate the dynamics equations and variational equations. In that case, it makes the calculation amount of orbit determination reduce substantially relative to the dynamical orbit determination method. The technique not only has a certain theoretical significance, but also can be as a conventional algorithm in the spacecraft orbit determination.

  1. Rare earth chalcogenides for use as high temperature thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Michiels, Jhn [Iowa State Univ., Ames, IA (United States)

    1996-01-02

    In the first part of the thesis, the electric resistivity, Seebeck coefficient, and Hall effect were measured in Xy(Y2S3)1-y (X = Cu, B, or Al), for y = 0.05 (Cu, B) or 0.025-0.075 for Al, in order to determine their potential as high- temperature (HT)(300-1000 C) thermoelectrics. Results indicate that Cu, B, Al- doped Y2S3 are not useful as HT thermoelectrics. In the second part, phase stability of γ-cubic LaSe1.47-1.48 and NdSe1.47 was measured periodically during annealing at 800 or 1000 C for the same purpose. In the Nd selenide, β phase increased with time, while the Nd selenide showed no sign of this second phase. It is concluded that the La selenide is not promising for use as HT thermoelectric due to the γ-to-β transformation, whereas the Nd selenide is promising.

  2. Extrascleral extension of choroidal melanoma: post-enucleation high-dose-rate interstitial brachytherapy of the orbit.

    Science.gov (United States)

    Finger, Paul T; Tena, Lawrence B; Semenova, Ekaterina; Aridgides, Paul; Choi, Walter H

    2014-01-01

    To investigate if orbital extension of uveal melanoma can be treated with high-dose-rate (HDR) brachytherapy. This study is a retrospective analysis of the results of a clinical case series was performed on 10 patients. Each underwent primary enucleation for uveal melanoma, was discovered to have orbital extension, and consented for HDR brachytherapy. By American Joint Committee on Cancer (AJCC) initial tumor grading, there was one each (T1c, T2c, T2d, and T3d, three T4c, and two T4d-staged uveal melanomas. One was AJCC-staged R2 due to orbital recurrence presenting 16 months after enucleation. (192)Ir HDR brachytherapy involved transcutaneous circumferential orbital incisions allowing for evenly spaced brachytherapy catheters into the orbit. A target dose of 32.85 Gy (range, 32.85-34 Gy) was delivered in 9-10 twice-daily fractions (range, 3.4-3.65 Gy per fraction) over 5 consecutive days. Data analysis included but was not limited to radiation therapy methods, local tumor control, side effects, and metastatic rate. In the 9 patients who tolerated treatment, there has been no orbital recurrence at a median follow-up of 18 months (range, 1-62 months). Four patients died of metastatic disease (one presented with a treated solitary liver metastasis before brachytherapy). There was no significant eyelash or eyebrow loss. There was no radiation-induced eyelid erythema, orbital infection, or contracted sockets. All orbits accepted and maintained ocular prostheses. Brachytherapy was used as an alternative to external beam radiation treatment for postenucleation orbital melanoma. This series reports complete local control, few side effects, and excellent cosmetic results. Copyright © 2014 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  3. High-frequency signals of oceans and atmosphere in Earth rotation

    Science.gov (United States)

    Böhm, S.; Nilsson, T.; Schindelegger, M.; Schuh, H.

    2012-04-01

    Dynamic processes in the atmosphere and oceans with diurnal and sub-diurnal variability leave measurable short-period footprints in polar motion and length of day (LOD)/Universal Time (UT1). The integral effect of all geophysical and extra-terrestrial influences is seen in the Earth rotation variations observed by space geodetic techniques. Allocating the signal components to their generating mechanisms requires appropriate model representations of the individual phenomena. We give a general overview of the known geophysical effects on Earth rotation from sub-daily to multi-annual time scales with particular attention paid to the high-frequency impact of the oceans and atmosphere. The signals are examined in terms of geophysical modeling as well as with regard to Earth rotation observations. Recent results from the analysis of numerical weather model data and available ocean tide models with respect to sub-daily Earth rotation excitation are shown. As to the observational aspect, we illustrate different methods for the determination of short-period Earth rotation variations by means of VLBI (Very Long Baseline Interferometry) and present respective results, obtained from the analysis of 24-hour sessions covering the years 1984-2010. Furthermore the potential of a combined analysis of VLBI and ring laser measurements, concerning the estimation of Earth rotation parameters with sub-diurnal resolution, is outlined.

  4. Using Authentic Data in High School Earth System Science Research - The Students' Perspective

    Science.gov (United States)

    Getzandanner, K.; Luhn, B.; Smith, B.

    2006-05-01

    Using real science data in a science research class has been an effective way to learn the scientific process, problem solving, and communication skills. At Catoctin High School in Thurmont, MD we participated in a course that has been developed to hone scientific research skills, and inspire our interest in careers in science and technology. The Earth System Science Research course has provided us with an opportunity to study Earth System Science using the latest information gathered through current technologies. The system approach to this course helped us to understand the complexity and interrelatedness of the Earth system. This course is an elective offering that has engaged us in all of the spheres of Earth's system. This course allowed us to utilize skills we gained from previous science courses to study the physical, chemical, and biological aspects of the Earth system. It allowed us to study aspects of Earth's spheres that interested us most as individuals. We were treated more like real researchers and not boxed in by old-fashioned science curriculum. We were required to produce a scientific presentation to communicate the results of our research. These results were then presented to scientists at the Goddard Space Flight Center.

  5. Potential seal candidates for high-energy propellants. [for Space Shuttle orbital maneuvering system

    Science.gov (United States)

    Merz, P. L.

    1975-01-01

    Five potential seal candidates (linear Tefzel, linear Halar, crosslinked Halar, Viton ECD-006, and phosphazine fluoroelastomer) were evaluated for the orbital maneuvering system of the space shuttle. Since this system employs nitrogen tetroxide (N2O4) and monomethyl hydrazine (MMH) as hypergolic propellants, the seal candidates were selected on the basis of projected chemical resistance as well as rheological behavior. Chemical resistance to these high-energy fuels was determined via conventional isothermal and thermal cycling immersion tests. Rheological measurements, however, were performed on O-rings molded from the subject seal candidates. Properties determined, such as cyclic work and hysteresis, stress relaxation, and indicated modulus, therefore, relate to the O-ring seals themselves.

  6. High efficiency frequency upconversion of photons carrying orbital angular momentum for a quantum information interface.

    Science.gov (United States)

    Tang, Ruikai; Li, Xiongjie; Wu, Wenjie; Pan, Haifeng; Zeng, Heping; Wu, E

    2015-04-20

    The orbital angular momentum (OAM) of light shows great potential in quantum communication. The transmission wavelength for telecom is usually around 1550 nm, while the common quantum information storage and processing devices based on atoms, ions or NV color centers are for photons in visible regime. Here we demonstrate a quantum information interface based on the frequency upconversion for photons carrying OAM states from telecom wavelength to visible regime by sum-frequency generation with high quantum conversion efficiency. The infrared photons at 1558 nm carrying different OAM values were converted to the visible regime of 622.2 nm, and the OAM value of the signal photons was well preserved in the frequency upconversion process with pump beam in Gaussian profile.

  7. Spin-Orbit Torque from a Magnetic Heterostructure of High-Entropy Alloy

    Science.gov (United States)

    Chen, Tian-Yue; Chuang, Tsao-Chi; Huang, Ssu-Yen; Yen, Hung-Wei; Pai, Chi-Feng

    2017-10-01

    High-entropy alloy (HEA) is a family of metallic materials with nearly equal partitions of five or more metals, which might possess mechanical and transport properties that are different from conventional binary or tertiary alloys. In this work, we demonstrate current-induced spin-orbit torque (SOT) magnetization switching in a Ta-Nb-Hf-Zr-Ti HEA-based magnetic heterostructure with perpendicular magnetic anisotropy. The maximum dampinglike SOT efficiency from this particular HEA-based magnetic heterostructure is further determined to be |ζDLHEA | ≈0.033 by hysteresis-loop-shift measurements, while that for the Ta control sample is |ζDLTa | ≈0.04 . Our results indicate that HEA-based magnetic heterostructures can serve as an alternative group of potential candidates for SOT device applications due to the possibility of tuning buffer-layer properties with more than two constituent elements.

  8. Improving sensitivity of residual current transformers to high frequency earth fault currents

    Directory of Open Access Journals (Sweden)

    Czapp Stanislaw

    2017-09-01

    Full Text Available For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.

  9. High-capacity millimetre-wave communications with orbital angular momentum multiplexing

    National Research Council Canada - National Science Library

    Yan, Yan; Xie, Guodong; Lavery, Martin P J; Huang, Hao; Ahmed, Nisar; Bao, Changjing; Ren, Yongxiong; Cao, Yinwen; Li, Long; Zhao, Zhe; Molisch, Andreas F; Tur, Moshe; Padgett, Miles J; Willner, Alan E

    2014-01-01

    .... Such orbital angular momentum based multiplexing can potentially increase the system capacity and spectral efficiency of millimetre-wave wireless communication links with a single aperture pair...

  10. High-performance technology for indexing of high volumes of Earth remote sensing data

    Science.gov (United States)

    Strotov, Valery V.; Taganov, Alexander I.; Kolesenkov, Aleksandr N.; Kostrov, Boris V.

    2017-10-01

    The present paper has suggested a technology for search, indexing, cataloging and distribution of aerospace images on the basis of geo-information approach, cluster and spectral analysis. It has considered information and algorithmic support of the system. Functional circuit of the system and structure of the geographical data base have been developed on the basis of the geographical online portal technology. Taking into account heterogeneity of information obtained from various sources it is reasonable to apply a geoinformation platform that allows analyzing space location of objects and territories and executing complex processing of information. Geoinformation platform is based on cartographic fundamentals with the uniform coordinate system, the geographical data base, a set of algorithms and program modules for execution of various tasks. The technology for adding by particular users and companies of images taken by means of professional and amateur devices and also processed by various software tools to the array system has been suggested. Complex usage of visual and instrumental approaches allows significantly expanding an application area of Earth remote sensing data. Development and implementation of new algorithms based on the complex usage of new methods for processing of structured and unstructured data of high volumes will increase periodicity and rate of data updating. The paper has shown that application of original algorithms for search, indexing and cataloging of aerospace images will provide an easy access to information spread by hundreds of suppliers and allow increasing an access rate to aerospace images up to 5 times in comparison with current analogues.

  11. Deep learning as a tool to distinguish between high orbital angular momentum optical modes

    Science.gov (United States)

    Knutson, E. M.; Lohani, Sanjaya; Danaci, Onur; Huver, Sean D.; Glasser, Ryan T.

    2016-09-01

    The generation of light containing large degrees of orbital angular momentum (OAM) has recently been demon- strated in both the classical and quantum regimes. Since there is no fundamental limit to how many quanta of OAM a single photon can carry, optical states with an arbitrarily high difference in this quantum number may, in principle, be entangled. This opens the door to investigations into high-dimensional entanglement shared between states in superpositions of nonzero OAM. Additionally, making use of non-zero OAM states can allow for a dramatic increase in the amount of information carried by a single photon, thus increasing the information capacity of a communication channel. In practice, however, it is difficult to differentiate between states with high OAM numbers with high precision. Here we investigate the ability of deep neural networks to differentiate between states that contain large values of OAM. We show that such networks may be used to differentiate be- tween nearby OAM states that contain realistic amounts of noise, with OAM values of up to 100. Additionally, we examine how the classification accuracy scales with the signal-to-noise ratio of images that are used to train the network, as well as those being tested. Finally, we demonstrate the simultaneous classification of < 100 OAM states with greater than 70 % accuracy. We intend to verify our system with experimentally-produced classi- cal OAM states, as well as investigate possibilities that would allow this technique to work in the few-photon quantum regime.

  12. A Tapestry of Orbits

    Science.gov (United States)

    King-Hele, D. G.

    2005-07-01

    Satellites as they cross the night sky look like moving stars, which can be accurately tracked by an observer with binoculars as well as by giant radars and large cameras. These observations help to determine the satellite's orbit, which is sensitive to the drag of the upper atmosphere and to any irregularities in the gravity field of the Earth. Analysis of the orbit can be used to evaluate the density of the upper atmosphere and to define the shape of the Earth. Desmond King-Hele was the pioneer of this technique of orbit analysis, and this book tells us how the research began, before the launch of Sputnik in 1957. For thirty years King-Hele and his colleagues at the Royal Aircraft Establishment, Farnborough, developed and applied the technique to reveal much about the Earth and air at a very modest cost. In the 1960s the upper-atmosphere density was thoroughly mapped out for 100 to 2000 km, revealing immense variation of density with solar activity and between day and night. In the 1970s and 1980s a picture of the upper-atmosphere winds emerged, and the profile of the pear-shaped Earth was accurately charted. The number of satellites now orbiting the earth is over 5000. This book is the story of how this inexpensive research of their orbits developed to yield a rich harvest of knowledge about the Earth and its atmosphere, in a scientific narrative that is enlivened with many personal experiences.

  13. Spin crossover and Mott—Hubbard transition under high pressure and high temperature in the low mantle of the Earth

    Science.gov (United States)

    Ovchinnikov, S. G.; Ovchinnikova, T. M.; Plotkin, V. V.; Dyad'kov, P. G.

    2015-11-01

    Effect of high pressure induced spin crossover on the magnetic, electronic and structural properties of the minerals forming the Earth's low mantle is discussed. The low temperature P, T phase diagram of ferropericlase has the quantum phase transition point Pc = 56 GPa at T = 0 confirmed recently by the synchrotron Mössbauer spectroscopy. The LDA+GTB calculated phase diagram describes the experimental data. Its extension to the high temperature resulted earlier in prediction of the metallic properties of the Earth's mantle at the depth 1400 km insulator transition and compare them with the experimental seismic and geomagnetic field data.

  14. Extreme energetic electron fluxes in low Earth orbit: Analysis of POES E > 30, E > 100, and E > 300 keV electrons

    Science.gov (United States)

    Meredith, Nigel P.; Horne, Richard B.; Isles, John D.; Green, Janet C.

    2016-02-01

    Energetic electrons are an important space weather hazard. Electrons with energies less than about 100 keV cause surface charging, while higher-energy electrons can penetrate materials and cause internal charging. In this study we conduct an extreme value analysis of the maximum 3-hourly flux of E > 30 keV, E > 100 keV, and E > 300 keV electrons in low Earth orbit as a function of L∗, for geomagnetic field lines that map to the outer radiation belt, using data from the National Oceanic and Atmospheric Administration Polar Operational Environmental Satellites (POES) from July 1998 to June 2014. The 1 in 10 year flux of E > 30 keV electrons shows a general increasing trend with distance ranging from 1.8 × 107 cm-2 s-1 sr-1 at L∗=3.0 to 6.6 × 107 cm-2 s-1 sr-1 at L∗=8.0. The 1 in 10 year flux of E > 100 keV electrons peaks at L∗=4.5-5.0 at 1.9 × 107 cm-2 s-1 sr-1 decreasing to minima of 7.1 × 106 and 8.7 × 106 cm-2 s-1 sr-1 at L∗=3.0 and 8.0, respectively. In contrast to the E > 30 keV electrons, the 1 in 10 year flux of E > 300 keV electrons shows a general decreasing trend with distance, ranging from 2.4 × 106 cm-2 s-1 sr-1 at L∗=3.0 to 1.2 × 105 cm-2 s-1 sr-1 at L∗=8.0. Our analysis suggests that there is a limit to the E > 30 keV electrons with an upper bound in the range 5.1 × 107 to 8.8 × 107 cm-2 s-1 sr-1. However, the results suggest that there is no upper bound for the E > 100 keV and E > 300 keV electrons.

  15. The Orbital Experience: Building Community through Communication and Connections in High School Spanish Classes

    Science.gov (United States)

    Gomez, Diane W.; Gujarati, Joan; Heckendorn, Rick

    2012-01-01

    This article highlights the Orbital Experience (OE), a unique experience that explores the affective domains of second language acquisition, including communication in the target language, making interdisciplinary connections, and fostering a community of learners. Through Orbitals, students serve as experts by researching a topic of interest,…

  16. Automatic Detection of Changes on Mars Surface from High-Resolution Orbital Images

    Science.gov (United States)

    Sidiropoulos, Panagiotis; Muller, Jan-Peter

    2017-04-01

    Over the last 40 years Mars has been extensively mapped by several NASA and ESA orbital missions, generating a large image dataset comprised of approximately 500,000 high-resolution images (of resources, which is very difficult to achieve when dealing with a rapidly increasing volume of data. Although citizen science can be employed for training and verification it is unsuitable for planetwide systematic change detection. In this work, we introduce a novel approach in planetary image change detection, which involves a batch-mode automatic change detection pipeline that identifies regions that have changed. This is tested in anger, on tens of thousands of high-resolution images over the MC11 quadrangle [5], acquired by CTX, HRSC, THEMIS-VIS and MOC-NA instruments [1]. We will present results which indicate a substantial level of activity in this region of Mars, including instances of dynamic natural phenomena that haven't been cataloged in the planetary science literature before. We will demonstrate the potential and usefulness of such an automatic approach in planetary science change detection. Acknowledgments: The research leading to these results has received funding from the STFC "MSSL Consolidated Grant" ST/K000977/1 and partial support from the European Union's Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n° 607379. References: [1] P. Sidiropoulos and J. - P. Muller (2015) On the status of orbital high-resolution repeat imaging of Mars for the observation of dynamic surface processes. Planetary and Space Science, 117: 207-222. [2] O. Aharonson, et al. (2003) Slope streak formation and dust deposition rates on Mars. Journal of Geophysical Research: Planets, 108(E12):5138 [3] A. McEwen, et al. (2011) Seasonal flows on warm martian slopes. Science, 333 (6043): 740-743. [4] S. Byrne, et al. (2009) Distribution of mid-latitude ground ice on mars from new impact craters. Science, 325(5948):1674-1676. [5] K. Gwinner, et al (2016) The High

  17. Assessing Earth and Environmental Science Enrollment Trends in Texas Public High Schools

    Science.gov (United States)

    Sanders, Joan G.

    2012-01-01

    Scope and Method of Study: This study assesses the status of Earth and environmental sciences education in Texas Public High Schools by analyzing enrollment proportions of 11th and 12th grade students in 607 Independent School Districts (ISD) for the 2010-2011 academic school year using a quantitative, non-experimental alpha research design. This…

  18. Spacecraft Orbit Determination with The B-spline Approximation Method

    Science.gov (United States)

    Song, Ye-zhi; Huang, Yong; Hu, Xiao-gong; Li, Pei-jia; Cao, Jian-feng

    2014-04-01

    It is known that the dynamical orbit determination is the most common way to get the precise orbits of spacecraft. However, it is hard to build up the precise dynamical model of spacecraft sometimes. In order to solve this problem, the technique of the orbit determination with the B-spline approximation method based on the theory of function approximation is presented in this article. In order to verify the effectiveness of this method, simulative orbit determinations in the cases of LEO (Low Earth Orbit), MEO (Medium Earth Orbit), and HEO (Highly Eccentric Orbit) satellites are performed, and it is shown that this method has a reliable accuracy and stable solution. The approach can be performed in both the conventional celestial coordinate system and the conventional terrestrial coordinate system. The spacecraft's position and velocity can be calculated directly with the B-spline approximation method, it needs not to integrate the dynamical equations, nor to calculate the state transfer matrix, thus the burden of calculations in the orbit determination is reduced substantially relative to the dynamical orbit determination method. The technique not only has a certain theoretical significance, but also can serve as a conventional algorithm in the spacecraft orbit determination.

  19. High-energy neutrino attenuation in the Earth and its associated uncertainties

    Science.gov (United States)

    Vincent, Aaron C.; Argüelles, Carlos A.; Kheirandish, Ali

    2017-11-01

    We describe νFATE: Neutrino Fast Attenuation Through Earth, a very rapid method of accurately computing the attenuation of high-energy neutrinos during their passage through Earth to detectors such as IceCube, ANTARES or KM3Net, including production of secondary neutrinos from τ± lepton decay. We then use this method to quantify the error on attenuation due to uncertainties in the isotropic neutrino spectrum, the composition of the Earth, and the parton distribution functions. We show that these can be as large as 20%, which can significantly impact reconstructed astrophysical neutrino parameters, as well as searches for new physics. An implementation of this algorithm is provided as a public code.

  20. High Resolution Infrared Radiative Transfer of Earth-like planets Influenced by Multiple Clouds

    Science.gov (United States)

    Vasquez, Mayte; Schreier, Franz; Trautmann, Thomas; Rauer, Heike; Kitzmann, Daniel; Patzer, A. B. C.; Gimeno Garc&ía, Sebastián.

    2012-07-01

    Background:, The emission spectrum of the modern Earth around different types of stars has been modeled in order to study the effects of different incident stellar radiation in the atmosphere. The Earth-like planetary spectra have also been studied in the presence of clouds. Clouds have an impact on the radiative transfer in planetary atmospheres by changing the spectra (intensities and shapes) due to extinction events (scattering and absorption). Thereby, they can influence the atmospheric and surface temperatures and can also generate false-negative biomarker signatures. Methods:, The spectra of Earth-like have been modeled using a line-by-line radiative transfer model coupled with a multiple scattering solver. The atmospheres of these planets were calculated using a convective climate model taking as reference the atmospheric profile from the modern Earth. All main molecular bands found in the thermal region (H2O, CO2, N2O, CH4 and O3) were analyzed at high resolution in order to assess their detectability in the presence of low (water) and high-level (ice) clouds for different percent coverage. Results:, The resulting calculations indicate that the modern Earth spectrum for a cloud-free atmosphere changes in the presence of different stellar types. The pressure-temperature profile and the molecular concentrations of the Earth were altered. In the presence of clouds, the atmospheric temperatures were modified as well. The water cloud cooled down the surface and tropospheric temperatures of the planets while the ice cloud warmed them up. The presence of clouds also decreased the depth of the absorption bands and modified their shapes, consequently producing a false-negative detection of some of the bands. Keywords:, radiation, planets, atmospheres, clouds, aerosols, molecules, scattering, habitability, modeling.

  1. Mars Molniya Orbit Atmospheric Resource Mining

    Science.gov (United States)

    Mueller, Robert P.; Braun, Robert D.; Sibille, Laurent; Sforzo, Brandon; Gonyea, Keir; Ali, Hisham

    2016-01-01

    This NIAC (NASA Advanced Innovative Concepts) work will focus on Mars and will build on previous efforts at analyzing atmospheric mining at Earth and the outer solar system. Spacecraft systems concepts will be evaluated and traded, to assess feasibility. However the study will primarily examine the architecture and associated missions to explore the closure, constraints and critical parameters through sensitivity studies. The Mars atmosphere consists of 95.5 percent CO2 gas which can be converted to methane fuel (CH4) and Oxidizer (O2) for chemical rocket propulsion, if hydrogen is transported from electrolyzed water on the Mars surface or from Earth. By using a highly elliptical Mars Molniya style orbit, the CO2 atmosphere can be scooped, ram-compressed and stored while the spacecraft dips into the Mars atmosphere at periapsis. Successive orbits result in additional scooping of CO2 gas, which also serves to aerobrake the spacecraft, resulting in a decaying Molniya orbit.

  2. Demonstrating High-Accuracy Orbital Access Using Open-Source Tools

    Science.gov (United States)

    Gilbertson, Christian; Welch, Bryan

    2017-01-01

    Orbit propagation is fundamental to almost every space-based analysis. Currently, many system analysts use commercial software to predict the future positions of orbiting satellites. This is one of many capabilities that can replicated, with great accuracy, without using expensive, proprietary software. NASAs SCaN (Space Communication and Navigation) Center for Engineering, Networks, Integration, and Communications (SCENIC) project plans to provide its analysis capabilities using a combination of internal and open-source software, allowing for a much greater measure of customization and flexibility, while reducing recurring software license costs. MATLAB and the open-source Orbit Determination Toolbox created by Goddard Space Flight Center (GSFC) were utilized to develop tools with the capability to propagate orbits, perform line-of-sight (LOS) availability analyses, and visualize the results. The developed programs are modular and can be applied for mission planning and viability analysis in a variety of Solar System applications. The tools can perform 2 and N-body orbit propagation, find inter-satellite and satellite to ground station LOS access (accounting for intermediate oblate spheroid body blocking, geometric restrictions of the antenna field-of-view (FOV), and relativistic corrections), and create animations of planetary movement, satellite orbits, and LOS accesses. The code is the basis for SCENICs broad analysis capabilities including dynamic link analysis, dilution-of-precision navigation analysis, and orbital availability calculations.

  3. Earth Pressure at rest of Søvind Marl – a highly overconsolidated Eocene clay

    DEFF Research Database (Denmark)

    Grønbech, Gitte Lyng; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl

    2016-01-01

    in situ stresses to various stress levels to estimate continuous K0 development in this highly overconsolidated clay. The normally consolidated earth pressure at rest was found for two different sample ages of Søvind Marl to be between 0.42 and 0.68. Results indicated the overconsolidated K0 reached......The present study evaluated earth pressure at rest, K0, in highly overconsolidated Eocene clay called Søvind Marl, which exhibits extremely high plasticity indices of up to 300%, a highly fissured structure, and preconsolidation stresses up to 6,800 kPa. Continuous Loading Oedometer (CLO) tests......, showed congruent results using α = 1.05 independent of sample age....

  4. Orbiting observatory SOHO finds source of high-speed "wind" blowing from the Sun

    Science.gov (United States)

    1999-02-01

    "The search for the source of the solar wind has been like the hunt for the source of the Nile," said Dr. Don Hassler of the Southwest Research Institute, Boulder, Colorado, lead author of the paper in Science. "For 30 years, scientists have observed high-speed solar wind coming from regions in the solar atmosphere with open magnetic field lines, called coronal holes. However, only recently, with the observations from SOHO, have we been able to measure the detailed structure of this source region". The solar wind comes in two varieties : high-speed and low-speed. The low-speed solar wind moves at "only" 1.5 million kilometres per hour, while the high-speed wind is even faster, moving at speeds as high as 3 million kilometres per hour. As it flows past Earth, the solar wind changes the shape and structure of the Earth's magnetic field. In the past, the solar wind didn't affect us directly, but as we become increasingly dependent on advanced technology, we become more susceptible to its effects. Researchers are learning that variations in the solar wind flow can cause dramatic changes in the shape of the Earth's magnetic field, which can damage satellites and disrupt communications and electrical power systems. The nature and origin of the solar wind is one of the main mysteries ESA's solar observatory SOHO was designed to solve. It has long been thought that the solar wind flows from coronal holes; what is new is the discovery that these outflows are concentrated in specific patches at the edges of the honeycomb-shaped magnetic fields. Just below the surface of the Sun there are large convection cells, and each cell has a magnetic field associated with it. "If one thinks of these cells as paving stones in a patio, then the solar wind is breaking through like grass around the edges, concentrated in the corners where the paving stones meet", said Dr. Helen Mason, University of Cambridge, England, and co-author of the paper to appear in Science. "However, at speeds

  5. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    Science.gov (United States)

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  6. Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

    Science.gov (United States)

    Way, M. J.; Aleinov, I.; Amundsen, David S.; Chandler, M. A.; Clune, T. L.; Del Genio, A.; Fujii, Y.; Kelley, M.; Kiang, N. Y.; Sohl, L.; hide

    2017-01-01

    Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower to more rapid than modern Earth's, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn's moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.

  7. High resolution chronology of late Cretaceous-early Tertiary events determined from 21,000 yr orbital-climatic cycles in marine sediments

    Science.gov (United States)

    Herbert, Timothy D.; Dhondt, Steven

    1988-01-01

    A number of South Atlantic sites cored by the Deep Sea Drilling Project (DSDP) recovered late Cretaceous and early Tertiary sediments with alternating light-dark, high-low carbonate content. The sedimentary oscillations were turned into time series by digitizing color photographs of core segments at a resolution of about 5 points/cm. Spectral analysis of these records indicates prominent periodicity at 25 to 35 cm in the Cretaceous intervals, and about 15 cm in the early Tertiary sediments. The absolute period of the cycles that is determined from paleomagnetic calibration at two sites is 20,000 to 25,000 yr, and almost certainly corresponds to the period of the earth's precessional cycle. These sequences therefore contain an internal chronometer to measure events across the K/T extinction boundary at this scale of resolution. The orbital metronome was used to address several related questions: the position of the K/T boundary within magnetic chron 29R, the fluxes of biogenic and detrital material to the deep sea immediately before and after the K/T event, the duration of the Sr anomaly, and the level of background climatic variability in the latest Cretaceous time. The carbonate/color cycles that were analyzed contain primary records of ocean carbonate productivity and chemistry, as evidenced by bioturbational mixing of adjacent beds and the weak lithification of the rhythmic sequences. It was concluded that sedimentary sequences that contain orbital cyclicity are capable of providing resolution of dramatic events in earth history with much greater precision than obtainable through radiometric methods. The data show no evidence for a gradual climatic deterioration prior to the K/T extinction event, and argue for a geologically rapid revolution at this horizon.

  8. The effects of different footprint sizes and cloud algorithms on the top-of-atmosphere radiative flux calculation from the Clouds and Earth's Radiant Energy System (CERES) instrument on Suomi National Polar-orbiting Partnership (NPP)

    Science.gov (United States)

    Su, Wenying; Liang, Lusheng; Miller, Walter F.; Sothcott, Victor E.

    2017-10-01

    Only one Clouds and Earth's Radiant Energy System (CERES) instrument is onboard the Suomi National Polar-orbiting Partnership (NPP) and it has been placed in cross-track mode since launch; it is thus not possible to construct a set of angular distribution models (ADMs) specific for CERES on NPP. Edition 4 Aqua ADMs are used for flux inversions for NPP CERES measurements. However, the footprint size of NPP CERES is greater than that of Aqua CERES, as the altitude of the NPP orbit is higher than that of the Aqua orbit. Furthermore, cloud retrievals from the Visible Infrared Imaging Radiometer Suite (VIIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS), which are the imagers sharing the spacecraft with NPP CERES and Aqua CERES, are also different. To quantify the flux uncertainties due to the footprint size difference between Aqua CERES and NPP CERES, and due to both the footprint size difference and cloud property difference, a simulation is designed using the MODIS pixel-level data, which are convolved with the Aqua CERES and NPP CERES point spread functions (PSFs) into their respective footprints. The simulation is designed to isolate the effects of footprint size and cloud property differences on flux uncertainty from calibration and orbital differences between NPP CERES and Aqua CERES. The footprint size difference between Aqua CERES and NPP CERES introduces instantaneous flux uncertainties in monthly gridded NPP CERES measurements of less than 4.0 W m-2 for SW (shortwave) and less than 1.0 W m-2 for both daytime and nighttime LW (longwave). The global monthly mean instantaneous SW flux from simulated NPP CERES has a low bias of 0.4 W m-2 when compared to simulated Aqua CERES, and the root-mean-square (RMS) error is 2.2 W m-2 between them; the biases of daytime and nighttime LW flux are close to zero with RMS errors of 0.8 and 0.2 W m-2. These uncertainties are within the uncertainties of CERES ADMs. When both footprint size and cloud property

  9. The effects of different footprint sizes and cloud algorithms on the top-of-atmosphere radiative flux calculation from the Clouds and Earth's Radiant Energy System (CERES instrument on Suomi National Polar-orbiting Partnership (NPP

    Directory of Open Access Journals (Sweden)

    W. Su

    2017-10-01

    Full Text Available Only one Clouds and Earth's Radiant Energy System (CERES instrument is onboard the Suomi National Polar-orbiting Partnership (NPP and it has been placed in cross-track mode since launch; it is thus not possible to construct a set of angular distribution models (ADMs specific for CERES on NPP. Edition 4 Aqua ADMs are used for flux inversions for NPP CERES measurements. However, the footprint size of NPP CERES is greater than that of Aqua CERES, as the altitude of the NPP orbit is higher than that of the Aqua orbit. Furthermore, cloud retrievals from the Visible Infrared Imaging Radiometer Suite (VIIRS and the Moderate Resolution Imaging Spectroradiometer (MODIS, which are the imagers sharing the spacecraft with NPP CERES and Aqua CERES, are also different. To quantify the flux uncertainties due to the footprint size difference between Aqua CERES and NPP CERES, and due to both the footprint size difference and cloud property difference, a simulation is designed using the MODIS pixel-level data, which are convolved with the Aqua CERES and NPP CERES point spread functions (PSFs into their respective footprints. The simulation is designed to isolate the effects of footprint size and cloud property differences on flux uncertainty from calibration and orbital differences between NPP CERES and Aqua CERES. The footprint size difference between Aqua CERES and NPP CERES introduces instantaneous flux uncertainties in monthly gridded NPP CERES measurements of less than 4.0 W m−2 for SW (shortwave and less than 1.0 W m−2 for both daytime and nighttime LW (longwave. The global monthly mean instantaneous SW flux from simulated NPP CERES has a low bias of 0.4 W m−2 when compared to simulated Aqua CERES, and the root-mean-square (RMS error is 2.2 W m−2 between them; the biases of daytime and nighttime LW flux are close to zero with RMS errors of 0.8 and 0.2 W m−2. These uncertainties are within the uncertainties of CERES ADMs

  10. Optimal parking orbits for manned Mars missions

    Science.gov (United States)

    Cupples, Michael L.; Nordwall, Jill A.

    This paper summarizes a Mars parking orbit optimization effort. This parking orbit study includes the selection of optimal elliptic Mars parking orbits that meet mission constraints and that include pertinent apsidal misalignment losses. Mars missions examined are for the opportunity years of 2014, 2016, and 2018. For these mission opportunities, it is shown that the optimal parking orbits depend on the year that the mission occurs and are coupled with the outbound, Mars stay, and return phases of the mission. Constraints included in the parking orbit optimization process are periapsis lighting angle (related to a daylight landing requirement), periapsis latitude (related to a landing latitude range requirement) and the vehicle Trans-Earth-Injection stage mass. Also, effects of mission abort requirements on optimal parking orbits are investigated. Off-periapsis maneuvers for Mars orbit capture were found to be cost effective in reducing the mission delta-V for the 2016 abort from Mars capture scenario. The total capture and departure delta-V was `split' between the capture maneuver and the departure maneuver to reduce the 2016 Mars departure delta-V to below the level of the corresponding stage of the 2014 baseline mission. Landing results are provided that show Mars landing site access from the optimal elliptic parking orbits for Mars excursion vehicles with low (0.2) and high (1.3 and 1.6) lift to drag ratio.

  11. Lunar Orbiter Photo Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Orbiter Photo Gallery is an extensive collection of over 2,600 high- and moderate-resolution photographs produced by all five of the Lunar Orbiter...

  12. Charged particles radiation measurements with Liulin-MO dosimeter of FREND instrument aboard ExoMars Trace Gas Orbiter during the transit and in high elliptic Mars orbit

    Science.gov (United States)

    Semkova, Jordanka; Koleva, Rositza; Benghin, Victor; Dachev, Tsvetan; Matviichuk, Yuri; Tomov, Borislav; Krastev, Krasimir; Maltchev, Stephan; Dimitrov, Plamen; Mitrofanov, Igor; Malahov, Alexey; Golovin, Dmitry; Mokrousov, Maxim; Sanin, Anton; Litvak, Maxim; Kozyrev, Andrey; Tretyakov, Vladislav; Nikiforov, Sergey; Vostrukhin, Andrey; Fedosov, Fedor; Grebennikova, Natalia; Zelenyi, Lev; Shurshakov, Vyacheslav; Drobishev, Sergey

    2018-03-01

    ExoMars is a joint ESA-Rosscosmos program for investigating Mars. Two missions are foreseen within this program: one consisting of the Trace Gas Orbiter (TGO), that carries scientific instruments for the detection of trace gases in the Martian atmosphere and for the location of their source regions, plus an Entry, Descent and landing demonstrator Module (EDM), launched on March 14, 2016; and the other, featuring a rover and a surface platform, with a launch date of 2020. On October 19, 2016 TGO was inserted into high elliptic Mars' orbit. The dosimetric telescope Liulin-MO for measuring the radiation environment onboard the ExoMars 2016 TGO is a module of the Fine Resolution Epithermal Neutron Detector (FREND). Here we present first results from measurements of the charged particle fluxes, dose rates, Linear Energy Transfer (LET) spectra and estimation of dose equivalent rates in the interplanetary space during the cruise of TGO to Mars and first results from dosimetric measurements in high elliptic Mars' orbit. A comparison is made with the dose rates obtained by RAD instrument onboard Mars Science Laboratory during the cruise to Mars in 2011-2012 and with the Galactic Cosmic Rays (GCR) count rates provided by other particle detectors currently in space. The average measured dose rate in Si from GCR during the transit to Mars for the period April 22-September 15, 2016 is 372 ± 37 μGy d-1 and 390 ± 39 μGy d-1 in two perpendicular directions. The dose equivalent rate from GCR for the same time period is about 2 ± 0.3 mSv d-1. This is in good agreement with RAD results for radiation dose rate in Si from GCR in the interplanetary space, taking into account the different solar activity during the measurements of both instruments. About 10% increase of the dose rate, and 15% increase of the dose equivalent rate for 10.5 months flight is observed. It is due to the increase of Liulin-MO particle fluxes for that period and corresponds to the overall GCR intensity

  13. Satellite formation design in orbits of high eccentricity for missions with performance criteria specified over a region of interest

    Science.gov (United States)

    Roscoe, Christopher William Thomas

    Several methods are presented for the design of satellite formations for science missions in high-eccentricity reference orbits with quantifiable performance criteria specified throughout only a portion the orbit, called the Region of Interest (RoI). A modified form of the traditional average along-track drift minimization condition is introduced to account for the fact that performance criteria are only specified within the RoI, and a robust formation design algorithm (FDA) is defined to improve performance in the presence of formation initialization errors. Initial differential mean orbital elements are taken as the design variables and the Gim-Alfriend state transition matrix (G-A STM) is used for relative motion propagation. Using mean elements and the G-A STM allows for explicit inclusion of J2 perturbation effects in the design process. The methods are applied to the complete formation design problem of the NASA Magnetospheric Multiscale (MMS) mission and results are verified using the NASA General Mission Analysis Tool (GMAT). Since satellite formations in high-eccentricity orbits will spend long times at high altitude, third-body perturbations are an important design consideration as well. A detailed analytical analysis of third-body perturbation effects on satellite formations is also performed and averaged dynamics are derived for the particular case of the lunar perturbation. Numerical results of the lunar perturbation analysis are obtained for the example application of the MMS mission and verified in GMAT.

  14. Linked Autonomous Interplanetary Satellite Orbit Navigation

    Science.gov (United States)

    Parker, Jeffrey S.; Anderson, Rodney L.; Born, George H.; Leonard, Jason M.; McGranaghan, Ryan M.; Fujimoto, Kohei

    2013-01-01

    A navigation technology known as LiAISON (Linked Autonomous Interplanetary Satellite Orbit Navigation) has been known to produce very impressive navigation results for scenarios involving two or more cooperative satellites near the Moon, such that at least one satellite must be in an orbit significantly perturbed by the Earth, such as a lunar halo orbit. The two (or more) satellites track each other using satellite-to-satellite range and/or range-rate measurements. These relative measurements yield absolute orbit navigation when one of the satellites is in a lunar halo orbit, or the like. The geometry between a lunar halo orbiter and a GEO satellite continuously changes, which dramatically improves the information content of a satellite-to-satellite tracking signal. The geometrical variations include significant out-of-plane shifts, as well as inplane shifts. Further, the GEO satellite is almost continuously in view of a lunar halo orbiter. High-fidelity simulations demonstrate that LiAISON technology improves the navigation of GEO orbiters by an order of magnitude, relative to standard ground tracking. If a GEO satellite is navigated using LiAISON- only tracking measurements, its position is typically known to better than 10 meters. If LiAISON measurements are combined with simple radiometric ground observations, then the satellite s position is typically known to better than 3 meters, which is substantially better than the current state of GEO navigation. There are two features of LiAISON that are novel and advantageous compared with conventional satellite navigation. First, ordinary satellite-to-satellite tracking data only provides relative navigation of each satellite. The novelty is the placement of one navigation satellite in an orbit that is significantly perturbed by both the Earth and the Moon. A navigation satellite can track other satellites elsewhere in the Earth-Moon system and acquire knowledge about both satellites absolute positions and velocities

  15. ORION: A Supersynchronous Transfer Orbit mission

    Science.gov (United States)

    Walters, I. M.; Baker, J. F.; Shurmer, I. M.

    1995-01-01

    ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

  16. ORION: A Supersynchronous Transfer Orbit mission

    Science.gov (United States)

    Walters, I. M.; Baker, J. F.; Shurmer, I. M.

    1995-05-01

    ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

  17. Shear softening of Earth's inner core indicated by its high Poisson's ratio and elastic anisotropy

    CERN Document Server

    Wu, Zhongqing

    2016-01-01

    Earth's inner core exhibits an unusually high Poisson's ratio and noticeable elastic anisotropy. The mechanisms responsible for these features are critical for understanding the evolution of the Earth but remain unclear. This study indicates that once the correct formula for the shear modulus is used, shear softening can simultaneously explain the high Poisson's ratio and strong anisotropy of the inner core. Body-centred-cubic (bcc) iron shows shear instability at the pressures found in the inner-core and can be dynamically stabilized by temperature and light elements. It is very likely that some combinations of light elements stabilize the bcc iron alloy under inner-core conditions. Such a bcc phase would exhibit significant shear softening and match the geophysical constraints of the inner core. Identifying which light elements and what concentrations of these elements stabilize the bcc phase will provide critical information on the light elements of the inner core.

  18. High sucrolytic activity by invertase immobilized onto magnetic diatomaceous earth nanoparticles

    OpenAIRE

    Cabrera, Mariana P.; Assis, Caio R.D.; David F.M. Neri; Claudete F. Pereira; Fernando Soria; Luiz B. Carvalho, Jr.

    2017-01-01

    Invertase immobilized on magnetic diatomaceous earth nanoparticles (mDE-APTES-invertase) with high sucrolytic activity was obtained by an easy and low-cost method. An experimental design was carried out to investigate the best immobilization conditions and it allowed obtaining an immobilized derivative with a residual specific activity equal to 92.5%. Then, a second experimental design selected the mDE-APTES-invertase with higher specific activity in relation to other derivatives reported in ...

  19. THE DESIGN OF A HIGH PERFORMANCE EARTH IMAGERY AND RASTER DATA MANAGEMENT AND PROCESSING PLATFORM

    OpenAIRE

    Xie, Qingyun

    2016-01-01

    This paper summarizes the general requirements and specific characteristics of both geospatial raster database management system and raster data processing platform from a domain-specific perspective as well as from a computing point of view. It also discusses the need of tight integration between the database system and the processing system. These requirements resulted in Oracle Spatial GeoRaster, a global scale and high performance earth imagery and raster data management and processing pl...

  20. GOCE Satellite Orbit in a Computational Aspect

    Science.gov (United States)

    Bobojc, Andrzej; Drozyner, Andrzej

    2013-04-01

    The presented work plays an important role in research of possibility of the Gravity Field and Steady-State Ocean Circulation Explorer Mission (GOCE) satellite orbit improvement using a combination of satellite to satellite tracking high-low (SST- hl) observations and gravity gradient tensor (GGT) measurements. The orbit improvement process will be started from a computed orbit, which should be close to a reference ("true") orbit as much as possible. To realize this objective, various variants of GOCE orbit were generated by means of the Torun Orbit Processor (TOP) software package. The TOP software is based on the Cowell 8th order numerical integration method. This package computes a satellite orbit in the field of gravitational and non-gravitational forces (including the relativistic and empirical accelerations). The three sets of 1-day orbital arcs were computed using selected geopotential models and additional accelerations generated by the Moon, the Sun, the planets, the Earth and ocean tides, the relativity effects. Selected gravity field models include, among other things, the recent models from the GOCE mission and the models such as EIGEN-6S, EIGEN-5S, EIGEN-51C, ITG-GRACE2010S, EGM2008, EGM96. Each set of 1-day orbital arcs corresponds to the GOCE orbit for arbitrary chosen date. The obtained orbits were compared to the GOCE reference orbits (Precise Science Orbits of the GOCE satellite delivered by the European Space Agency) using the root mean squares (RMS) of the differences between the satellite positions in the computed orbits and in the reference ones. These RMS values are a measure of performance of selected geopotential models in terms of GOCE orbit computation. The RMS values are given for the truncated and whole geopotential models. For the three variants with the best fit to the reference orbits, the empirical acceleration models were added to the satellite motion model. It allowed for further improving the fitting of computed orbits to the

  1. Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

    Energy Technology Data Exchange (ETDEWEB)

    Way, M. J.; Aleinov, I.; Amundsen, David S.; Chandler, M. A.; Genio, A. D. Del; Fujii, Y.; Kelley, M.; Kiang, N. Y.; Sohl, L.; Tsigaridis, K. [NASA Goddard Institute for Space Studies, New York, NY 10025 (United States); Clune, T. L. [Global Modeling and Assimilation Office, NASA Goddard Space Flight Center (United States)

    2017-07-01

    Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower to more rapid than modern Earth’s, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn’s moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.

  2. The role of high-pressure experiments on determining super-Earth properties

    Science.gov (United States)

    Valencia, Diana; O'Connell, Richard J.; Sasselov, Dimitar D.

    2009-08-01

    Super-Earths are the newest class of extra-solar planets with a mass range between about 1-10 M ⊕ . With their large masses, they experience very large internal pressures. The central pressure scales proportionately with mass, reaching values that require us to extend our understanding of rock and H2O behavior to such extreme conditions. Pressure also constrains the power law relationship between mass and radius of solid planets R˜ M β . The value for the exponent is 0.262≤ β≤0.274 as constrained by the different internal structure models for super-Earths, while it is 0.3 for planets between 5-50% the mass of Earth. Despite uncertainties in planetary composition, temperature structure and equation of state, the mass-radius relationship is robust, and thus, useful for inferring the expected signal in transit searches. In the next few years many super-Earths will be discovered and their masses and radii will be known with some uncertainty. Even without errors in both the data and structure models, a large number of compositions can fit the same average density. However, the follow-up observations with space telescopes will yield very precise radius measurements and even probe the atmospheres of super-Earths. This radius uncertainty will then be comparable to the current error derived from the equation of state used by the structure models. Thus, there is a need for accurate equations of state of solid planetary materials. Furthermore, information on the structure, such as the size and state of the core, crucially depends on the exact behavior of super-Earth materials (i.e. silicates, iron, iron alloy and ices) at high pressures and temperatures. In addition, information about the atmospheric composition of these planets may prove useful in constraining their interiors. Ultimately any inference on the structure of super-Earths, including information from atmospheres, depends on the precision of interior models, which in turn require accurate equations of

  3. Photon Self-Induced Spin to Orbital Conversion in TGG crystal at high laser power

    CERN Document Server

    Mosca, S; Karimi, E; Piccirillo, B; Marrucci, L; De Rosa, R; Genin, E; Milano, L; Santamato, E

    2010-01-01

    In this paper, we present experimental evidence of a newly discovered third-order nonlinear optical process Self-Induced Spin-to-Orbital Conversion (SISTOC) of the photon angular momentum. This effect is the physical mechanism at the origin of the depolarization of very intense laser beams propagating in isotropic materials. The SISTOC process, like self-focusing, is triggered by laser heating leading to a radial temperature gradient in the medium. In this work we tested the occurrence of SISTOC in a terbium gallium garnet (TGG) rod for an impinging laser power of about 100~W. To study the SISTOC process we used different techniques: polarization analysis, interferometry and tomography of the photon orbital angular momentum. Our results confirm, in particular, that the apparent depolarization of the beam is due to the occurrence of maximal entanglement between the spin and orbital angular momentum of the photons undergoing the SISTOC process. This explanation of the true nature of the depolarization mechanism...

  4. EUV high resolution imager on-board solar orbiter: optical design and detector performances

    Science.gov (United States)

    Halain, J. P.; Mazzoli, A.; Rochus, P.; Renotte, E.; Stockman, Y.; Berghmans, D.; BenMoussa, A.; Auchère, F.

    2017-11-01

    The EUV high resolution imager (HRI) channel of the Extreme Ultraviolet Imager (EUI) on-board Solar Orbiter will observe the solar atmospheric layers at 17.4 nm wavelength with a 200 km resolution. The HRI channel is based on a compact two mirrors off-axis design. The spectral selection is obtained by a multilayer coating deposited on the mirrors and by redundant Aluminum filters rejecting the visible and infrared light. The detector is a 2k x 2k array back-thinned silicon CMOS-APS with 10 μm pixel pitch, sensitive in the EUV wavelength range. Due to the instrument compactness and the constraints on the optical design, the channel performance is very sensitive to the manufacturing, alignments and settling errors. A trade-off between two optical layouts was therefore performed to select the final optical design and to improve the mirror mounts. The effect of diffraction by the filter mesh support and by the mirror diffusion has been included in the overall error budget. Manufacturing of mirror and mounts has started and will result in thermo-mechanical validation on the EUI instrument structural and thermal model (STM). Because of the limited channel entrance aperture and consequently the low input flux, the channel performance also relies on the detector EUV sensitivity, readout noise and dynamic range. Based on the characterization of a CMOS-APS back-side detector prototype, showing promising results, the EUI detector has been specified and is under development. These detectors will undergo a qualification program before being tested and integrated on the EUI instrument.

  5. Highly automated on-orbit operations of the NuSTAR telescope

    Science.gov (United States)

    Roberts, Bryce; Bester, Manfred; Dumlao, Renee; Eckert, Marty; Johnson, Sam; Lewis, Mark; McDonald, John; Pease, Deron; Picard, Greg; Thorsness, Jeremy

    2014-08-01

    UC Berkeley's Space Sciences Laboratory (SSL) currently operates a fleet of seven NASA satellites, which conduct research in the fields of space physics and astronomy. The newest addition to this fleet is a high-energy X-ray telescope called the Nuclear Spectroscopic Telescope Array (NuSTAR). Since 2012, SSL has conducted on-orbit operations for NuSTAR on behalf of the lead institution, principle investigator, and Science Operations Center at the California Institute of Technology. NuSTAR operations benefit from a truly multi-mission ground system architecture design focused on automation and autonomy that has been honed by over a decade of continual improvement and ground network expansion. This architecture has made flight operations possible with nominal 40 hours per week staffing, while not compromising mission safety. The remote NuSTAR Science Operation Center (SOC) and Mission Operations Center (MOC) are joined by a two-way electronic interface that allows the SOC to submit automatically validated telescope pointing requests, and also to receive raw data products that are automatically produced after downlink. Command loads are built and uploaded weekly, and a web-based timeline allows both the SOC and MOC to monitor the state of currently scheduled spacecraft activities. Network routing and the command and control system are fully automated by MOC's central scheduling system. A closed-loop data accounting system automatically detects and retransmits data gaps. All passes are monitored by two independent paging systems, which alert staff of pass support problems or anomalous telemetry. NuSTAR mission operations now require less than one attended pass support per workday.

  6. Numerical analysis of earthquake response of an ultra-high earth-rockfill dam

    Science.gov (United States)

    Dong, W. X.; Xu, W. J.; Yu, Y. Z.; Lv, H.

    2013-05-01

    Failure of high earth dams under earthquake may cause disastrous economic damage and loss of lives. It is necessary to conduct seismic safety assessment, and numerical analysis is an effective way. Solid-fluid interaction has a significant influence on the dynamic responses of geotechnical materials, which should be considered in the seismic analysis of earth dams. The initial stress field needed for dynamic computation is often obtained from postulation, without considering the effects of early construction and reservoir impounding. In this study, coupled static analyses are conducted to simulate the construction and impounding of an ultra-high earth rockfill dam in China. Then based on the initial static stress field, dynamic response of the dam is studied with fully coupled nonlinear method. Results show that excess pore water pressure accumulates gradually with earthquake and the maximum value occurs at the bottom of core. Acceleration amplification reaches the maximum at the crest as a result of whiplash effect. Horizontal and vertical permanent displacements both reach the maximum values at the dam crest.

  7. Earthshine observations at high spectral resolution: exploring and detecting metal lines in the Earth's upper atmosphere

    Science.gov (United States)

    González-Merino, B.; Pallé, E.; Motalebi, F.; Montañés-Rodríguez, P.; Kissler-Patig, M.

    2013-11-01

    Observations of the Earth as a planet using the earthshine technique (i.e. looking at the light reflected from the dark side of the Moon) have been used for climate and astrobiology studies. They provide information about the planetary albedo, a fundamental parameter of the Earth's energy balance. Here we present, for the first time, observations of the earthshine taken at high spectral resolution. The high spectral resolution was chosen in order to investigate the possibility of detecting metallic layers in the Earth's atmosphere of geological or meteoritic origin. The Spettrografo Alta Risoluzione Galileo echelle spectrograph at the Telescopio Nazionale Galileo in La Palma was used to acquire the earthshine data. Observations were carried out on several nights in 2011 February, with the spectral resolution set at 29 000, covering a spectral range from the near-ultraviolet (360 nm) to near-infrared (1011.9 nm). While we find evidence for the detection of a Na layer in the earthshine, other atomic species are not detected, perhaps due to the low signal-to-noise ratio of the observations and the difficult telluric corrections. The Na layer is found to vary between observation dates, which we speculate is due to physical variations in mesospheric Na concentrations.

  8. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    Science.gov (United States)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  9. High End Computing Technologies for Earth Science Applications: Trends, Challenges, and Innovations

    Science.gov (United States)

    Parks, John (Technical Monitor); Biswas, Rupak; Yan, Jerry C.; Brooks, Walter F.; Sterling, Thomas L.

    2003-01-01

    Earth science applications of the future will stress the capabilities of even the highest performance supercomputers in the areas of raw compute power, mass storage management, and software environments. These NASA mission critical problems demand usable multi-petaflops and exabyte-scale systems to fully realize their science goals. With an exciting vision of the technologies needed, NASA has established a comprehensive program of advanced research in computer architecture, software tools, and device technology to ensure that, in partnership with US industry, it can meet these demanding requirements with reliable, cost effective, and usable ultra-scale systems. NASA will exploit, explore, and influence emerging high end computing architectures and technologies to accelerate the next generation of engineering, operations, and discovery processes for NASA Enterprises. This article captures this vision and describes the concepts, accomplishments, and the potential payoff of the key thrusts that will help meet the computational challenges in Earth science applications.

  10. High quality factor nanophotonic resonators in bulk rare-earth doped crystals

    CERN Document Server

    Zhong, Tian; Kindem, Jonathan M; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Numerous bulk crystalline materials exhibit attractive nonlinear and luminescent properties for classical and quantum optical applications. A chip-scale platform for high quality factor optical nanocavities in these materials will enable new optoelectronic devices and quantum light-matter interfaces. In this article, photonic crystal nanobeam resonators fabricated using focused ion beam milling in bulk insulators, such as rare-earth doped yttrium orthosilicate and yttrium vanadate, are demonstrated. Operation in the visible, near infrared, and telecom wavelengths with quality factors up to 27,000 and optical mode volumes close to one cubic wavelength is measured. These devices enable new nanolasers, on-chip quantum optical memories, single photon sources, and non-linear devices at low photon numbers based on rare-earth ions. The techniques are also applicable to other luminescent centers and crystals.

  11. The Dimensions of the Orbital Cavity Based on High-Resolution Computed Tomography of Human Cadavers

    DEFF Research Database (Denmark)

    Felding, Ulrik Ascanius; Bloch, Sune Land; Buchwald, Christian von

    2016-01-01

    with the degree of enophthalmos. However, a large degree of biological variation between individuals may preclude such absolute values from being successful indicators for surgery.Stereological methods have been used to estimate orbital cavity volume in a few studies, but to date these have not been used...

  12. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation

    KAUST Repository

    Minenkov, Yury

    2017-03-07

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (<2 kcal mol-1) for some reactions of Na, Mg, Ca, Sr, Ba and Pb, while for a few reactions of Ca and Ba deviations up to 40 kcal mol-1 have been obtained. Large errors are both due to artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol-1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol-1, indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  13. High index contrast potassium double tungstate waveguides towards efficient rare-earth ion amplification on-chip

    NARCIS (Netherlands)

    Sefünç, Mustafa; Segerink, Franciscus B.; García Blanco, Sonia Maria

    2015-01-01

    Rare-earth ion doped KY(WO4)2 amplifiers are proposed to be a good candidate for many future applications by benefiting from the excellent gain characteristics of rare-earth ions, namely high bit rate amplification (

  14. The influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel

    Science.gov (United States)

    Chu, Rensheng; Mu, Shukun; Liu, Jingang; Li, Zhanjun

    2017-09-01

    In the current paper, it is analyzed for the influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel. It is observed for the structure for different heat input of the coarse-grained area. It is finest for the coarse grain with the high heat input of 200 kJ / cm and the coarse grain area with 400 kJ / cm is the largest. The performance with the heat input of 200 kJ / cm for -20 °C V-shaped notch oscillatory power is better than the heat input of 400 kJ / cm. The grain structure is the ferrite and bainite for different holding time. The grain structure for 5s holding time has a grain size of 82.9 μm with heat input of 200 kJ/cm and grain size of 97.9 μm for 10s holding time. For the inclusions for HSLA steel with adding rare earth, they are Al2O3-CaS inclusions in the Al2O3-CaS-CaO ternary phase diagram. At the same time, it can not be found for low melting calcium aluminate inclusions compared to the inclusions for the HSLA steel without rare earth. Most of the size for the inclusions is between 1 ~ 10μm. The overall grain structure is smaller and the welding performance is more excellent for adding rare earth.

  15. High-resolution sensing for precision agriculture: from Earth-observing satellites to unmanned aerial vehicles

    Science.gov (United States)

    McCabe, Matthew F.; Houborg, Rasmus; Lucieer, Arko

    2016-10-01

    With global population projected to approach 9 billion by 2050, it has been estimated that a 40% increase in cereal production will be required to satisfy the worlds growing nutritional demands. Any such increases in agricultural productivity are likely to occur within a system that has limited room for growth and in a world with a climate that is different from that of today. Fundamental to achieving food and water security, is the capacity to monitor the health and condition of agricultural systems. While space-agency based satellites have provided the backbone for earth observation over the last few decades, many developments in the field of high-resolution earth observation have been advanced by the commercial sector. These advances relate not just to technological developments in the use of unmanned aerial vehicles (UAVs), but also the advent of nano-satellite constellations that offer a radical shift in the way earth observations are now being retrieved. Such technologies present opportunities for improving our description of the water, energy and carbon cycles. Efforts towards developing new observational techniques and interpretative frameworks are required to provide the tools and information needed to improve the management and security of agricultural and related sectors. These developments are one of the surest ways to better manage, protect and preserve national food and water resources. Here we review the capabilities of recently deployed satellite systems and UAVs and examine their potential for application in precision agriculture.

  16. High-resolution sensing for precision agriculture: from Earth-observing satellites to unmanned aerial vehicles

    KAUST Repository

    McCabe, Matthew

    2016-10-25

    With global population projected to approach 9 billion by 2050, it has been estimated that a 40% increase in cereal production will be required to satisfy the worlds growing nutritional demands. Any such increases in agricultural productivity are likely to occur within a system that has limited room for growth and in a world with a climate that is different from that of today. Fundamental to achieving food and water security, is the capacity to monitor the health and condition of agricultural systems. While space-Agency based satellites have provided the backbone for earth observation over the last few decades, many developments in the field of high-resolution earth observation have been advanced by the commercial sector. These advances relate not just to technological developments in the use of unmanned aerial vehicles (UAVs), but also the advent of nano-satellite constellations that offer a radical shift in the way earth observations are now being retrieved. Such technologies present opportunities for improving our description of the water, energy and carbon cycles. Efforts towards developing new observational techniques and interpretative frameworks are required to provide the tools and information needed to improve the management and security of agricultural and related sectors. These developments are one of the surest ways to better manage, protect and preserve national food and water resources. Here we review the capabilities of recently deployed satellite systems and UAVs and examine their potential for application in precision agriculture.

  17. Phaethon Near Earth

    Science.gov (United States)

    Jewitt, David

    2017-08-01

    Planet-crossing asteroid (3200) Phaethon, source of the Geminid meteoroid stream, will pass close to Earth in December 2017. Observations with HST are proposed to image debris ejected from this object at 1 AU heliocentric distance, to estimate the ejection velocities as the Earth passes through the orbit plane, and to estimate the dust production rate for comparison with the rates needed to sustain the Geminid stream in steady-state. These measurements will help determine the mechanism behind the ejection of the Geminids, a long-standing puzzle. While the release of micron-sized particles (probably by thermal fracture) has been recorded at Phaethon's perihelion (0.14 AU), mass loss has never been detected otherwise, raising the puzzle of the ejection mechanism and duration. The close approach (0.07 AU) on December 17 gives a once-in-a-lifetime opportunity to observe Phaethon at high sensitivity with a resolution of a few kilometers.

  18. Human response to high-background radiation environments on Earth and in space

    Science.gov (United States)

    Durante, M.; Manti, L.

    2008-09-01

    The main long-term objective of the space exploration program is the colonization of the planets of the Solar System. The high cosmic radiation equivalent dose rate represents an inescapable problem for the safe establishment of permanent human settlements on these planets. The unshielded equivalent dose rate on Mars ranges between 100 and 200 mSv/year, depending on the Solar cycle and altitude, and can reach values as high as 360 mSv/year on the Moon. The average annual effective dose on Earth is about 3 mSv, nearly 85% of which comes from natural background radiation, reduced to less than 1 mSv if man-made sources and the internal exposure to Rn daughters are excluded. However, some areas on Earth display anomalously high levels of background radiation, as is the case with thorium-rich monazite bearing sand deposits where values 200 400 times higher than the world average can be found. About 2% of the world’s population live above 3 km and receive a disproportionate 10% of the annual effective collective dose due to cosmic radiation, with a net contribution to effective dose by the neutron component which is 3 4 fold that at sea level. Thus far, epidemiological studies have failed to show any adverse health effects in the populations living in these terrestrial high-background radiation areas (HBRA), which provide an unique opportunity to study the health implications of an environment that, as closely as possibly achievable on Earth, resembles the chronic exposure of future space colonists to higher-than-normal levels of ionizing radiation. Chromosomal aberrations in the peripheral blood lymphocytes from the HBRA residents have been measured in several studies because chromosomal damage represents an early biomarker of cancer risk. Similar cytogenetic studies have been recently performed in a cohort of astronauts involved in single or repeated space flights over many years. The cytogenetic findings in populations exposed to high dose-rate background radiation

  19. MUSIC/FAST, A PRE-DESIGN AND PRE-MISSION ANALYSIS TOOL FOR THE EARTH ATMOSPHERIC RE-ENTRY OF SPACECRAFT, CAPSULES AND DE-ORBITED SATELLITES

    OpenAIRE

    Sourgen, Frédéric; Prévereaud, Ysolde; Vérant, Jean-Luc; LAROCHE, Emmanuel; Moschetta, Jean-Marc

    2015-01-01

    The paper proposes an overview of the physical models developed/selected and implemented in the ONERA aerothermodynamic (ATD) engineering code FAST. This tool is used to quickly determine the pressure and heat flux surface distribution at the wall, as well as aerodynamic forces and moments coefficients in hypersonic regime for free-molecular, transitional and continuum flows, for realistic designs of space vehicles ranging from capsules to spacecrafts and for generic shapes of orbital debris ...

  20. Orbital maneuvers and space rendezvous

    Science.gov (United States)

    Butikov, Eugene I.

    2015-12-01

    Several possibilities of launching a space vehicle from the orbital station are considered and compared. Orbital maneuvers discussed in the paper can be useful in designing a trajectory for a specific space mission. The relative motion of orbiting bodies is investigated on examples of spacecraft rendezvous with the space station that stays in a circular orbit around the Earth. An elementary approach is illustrated by an accompanying simulation computer program and supported by a mathematical treatment based on fundamental laws of physics and conservation laws. Material is appropriate for engineers and other personnel involved in space exploration, undergraduate and graduate students studying classical physics and orbital mechanics.